Waterwise Gardener

NanSterman

Waterwise Gardener

Nan Sterman is an award-winning author, designer, educator, and leading California garden expert. For nearly 20 years, Nan has reported on horticulture, agriculture, and gardening in San Diego County. Her understanding of how traditional techniques combine with modern technology helps her teach clients about edible and environmentally friendly plants and gardens.

Nan is also the host, co-writer, and co-producer of the public television show, A Growing Passion, which explores the power of plants in our world. Nan’s most recent book is Hot Color, Dry Garden, available at bookstores, online, and from her website waterwisegardener.com.

The Otay Water District’s Pipeline, a quarterly newsletter, features a garden column by Nan. Her stories offer a guide to sustainable and low-maintenance gardening.

Pipeline Newsletter features by Nan Sterman:

Drought Proof Your Garden for New Watering Restrictions — summer 2022 issue

There is no denying we are in a very serious drought that is only getting worse. While San Diego County is not under drought restrictions now, the state has asked everyone to cut back water use by 10 to 20%.

The easiest place to cut back water use is outdoors, but likely not in the way you think. Rather than turn off your garden’s irrigation, first rethink, repurpose, and readjust. You CAN have a beautiful garden on a very low-water diet.

The point of irrigating is to get water into the soil to supply plant roots.

HOW MUCH TO WATER?

Rather than running your sprinklers daily or on a schedule that matches your neighbors’, or letting the gardener take charge, figure out how long and often your plants truly need water. Here is how:

How long to water: turn on each irrigation zone and let it run for the usual time. Use a soil probe or stick your finger into the soil to feel how deep the water has penetrated. The goal is to get the water deep down to the roots. If it isn’t that deep, run the zone again and repeat until the deep soil is wet. Note how long it took – that’s how long to water. Don’t be surprised if each zone needs a different run time. Remember though, under the current level 2 actions, you should not water your landscape using sprinklers for more than 10 minutes per watering station per day.

How often to water: do the Canary Test. Now that you know how long to water each zone, test how often to water. Run a zone using its new run time and mark that day on your calendar. Wait to water that zone again until the first plant in that zone starts to look a little droopy – that’s the canary. It may take five or 10 days or two weeks. Set that zone to run a day or two short of the time it takes for the canary to droop. Repeat for every irrigation zone in your garden. For detailed instructions for the Canary Test, visit tinyurl.com/canarytestgiveaway. Currently, under the level 2 actions, you should not irrigate more than three days a week.

How often to water changes through the seasons – more often in the heat of summer; less often in the cool of winter; in between spring and fall. Test in each season, then adjust the irrigation schedule. Keep the run time constant year-round.

SWITCH TO EFFICIENT IRRIGATION

Change overhead spray and old-fashioned drip irrigation to in-line drip irrigation.

Overhead irrigation wastes up to half the water it sprays (you pay for all that wasted water). Plus, why irrigate leaves when plants take water up through their roots? Old-style drip – single emitters at the end of tiny tubes – falls apart, clogs, and breaks, all of which wastes water. Switch to in-line drip instead. In-line drip has emitters embedded in the wall of the irrigation tubing. What looks like a hole from the outside is the port of a very sophisticated emitter that releases water drop by drop. The water penetrates directly into the soil to reach plant roots. It saturates the entire root zone to support plants efficiently and effectively (see video.kpbs.org/video/growing-passion-waterwise-wonderful).

MULCH BARE SOIL

Once there is water in the soil, keep it there as long as possible. A layer of mulch over drip irrigation lines serves as a water insulating blanket. Mulch vegetable gardens with straw. Mulch succulent gardens with rock. Mulch nonsucculent-ornamental gardens and orchards with aged or composted wood mulch. Layer mulch at least 3-inches thick. Renew regularly.

Don’t mulch gardens irrigated with overhead spray. It takes much more water to first saturate the mulch and then saturate the soil. Switch to in-line drip, then mulch.

Do not use weedcloth, landscape cloth, weed fabric, etc. All are the same. All keep water from penetrating into the soil. All keep mulch from integrating into the soil. None prevents weeds.

REPLACE YOUR LAWN

Lawns use as much water as swimming pools. Replace your lawn with beautiful drought-tolerant plants – not with artificial turf, which brings a host of other problems and doesn’t help battle climate change. Solarize or sheet mulch to kill your lawn this summer (visit kpbs.org/news/arts-culture/2016/04/26/growing-passion-bye-bye-grass-how-remove-your-lawn).

CHANGE YOUR PLANT PALETTE

We are fortunate to have a huge palette of beautiful drought-tolerant plants that grow beautifully in our gardens with little if any irrigation once plants are established. Choose from California native plants, plants from Australia, South Africa, the Mediterranean basin, and coastal Chile. For some inspiration, check out my latest book, “Hot Color Dry Garden,” waterwisegardener.com/product/hot-color-in-the-dry-garden, and watch kpbs.org/news/arts-culture/2016/05/04/growing-passion-after-lawn-gone-waterwise-gardens.

GO GRAY

Reuse the water from your washing machine, bathtub, shower, and sinks to water fruit trees and ornamental shrubs and trees. Washing machine gray water systems called “laundry to landscape” are easiest to install, require no permits, and are inexpensive. You won’t generate enough graywater to meet your entire garden’s needs but it can make a big difference.

NOTE: DO NOT use graywater for vegetable gardens (visit video kpbs.org/video/growing-passion-waterwise-wonderful).

SAVE HEATING WATER Put a bucket under the bathtub spout, shower, and kitchen sink to catch the water wasted while it warms. Use the water for container plants and those in the ground. It may be a “drop in the bucket,” but it can make a huge difference.

Essential Garden Tools Part I — spring 2022 issue

Spring is a great time to inventory your garden tools. Weed out what’s broken or simply doesn’t do its intended job. Replace those tools with higher-quality versions. With tools, like with anything else, you get what you pay for. Good quality tools should last 10 years or longer, especially if maintained properly. Spend a little more and take a little time to get a lot more use and life out of your tools.

Here are my favorite cutting and watering tools to get you started.

CUTTING TOOLS:

  • Bypass hand pruners are the number one tool for your garden toolbelt. Use pruners to remove smaller branches on trees and shrubs, to deadhead flowering perennials, and to cut back ornamental grasses and dried-out bulb leaves. Harvest your fruits, vegetables, and herbs. Don’t bother with cheap hand pruners. Felco and Corona brand pruners are in most professionals’ toolbelts. Each offers several assorted styles and sizes – the larger the pruner, the larger diameter it can cut. Before you buy, handle the pruner to find the best fit, feel, and function.
  • Bypass loppers are like bypass pruners on stilts. The cutting head sits atop 15- to 30-inches-long handles, depending on the lopper. Their length helps you reach overhead or deep into the center of a shrub or tree. It also gives you leverage for cutting thick branches. Like with hand pruners, some are heavy and some are light. Although the blades, not the weight, have the greatest bearing on functionality. While Corona and Felco both make excellent loppers, my favorite is a purple-handled Dramm lopper that I’ve had forever.
  • Sharp blades are essential for pruners and loppers. Dull tools shred branches and damage plants. The Corona 5-inch carbide file fits the pocket and my garden apron, keeping it close at hand. A few quick swipes of the file on the right surface and in the right direction keeps these tools sharp and ready.
  • Use a hand saw to cut away branches that are too thick for pruners and loppers. Don’t use a hack saw or a carpenter’s saw. Only pruning saws are designed for cutting branches. These saws are typically curved to increase cutting power and many fold to make them easy to carry.

When you work with pruning and cutting tools, they must be cleaned once you finish with one plant and before you move on to the next. Dirty pruners and saws can transmit viruses, bacteria, etc., from one plant to another. If a plant is infected, you can infect others by failing to clean your tools. To clean, spray the cutting blades with bathroom disinfectant. Allow it to sit for about a minute before wiping the blades with a clean rag. Next, lubricate any moving parts with household lubricant or mineral oil. Work it into the mechanisms, then wipe away the excess with a clean rag.

Here’s a nice tutorial on cleaning pruning and cutting tools: youtube.com/watch?v=vROuLbOuYq0

WATERING TOOLS:

  • Dramm Colorstorm hoses come in a rainbow of colors, but more importantly, these tough, durable, no-kink hoses outlast all others. I prefer the 3/4 inches in diameter professional hoses, but the 5/8 inches in diameter hoses are just as good. Hoses come in lengths from 25- to 100-feet-long. Keep in mind that the longer the hose, the heavier the hose.
  • Dramm One-Touch Rain Wand is THE BEST hose-end watering wand on the market. Forget spray guns with five or six spray settings. They are designed to wash cars and hose down sidewalks, not water plants. They blast plants out of the ground and blast them into smithereens. Dramm’s One-Touch Rain Wand is easy to hold, easy to use, and makes a gentle, full-shower rain that waters beautifully without destroying. Use your thumb to switch the water on and off. It’s effective and efficient.
  • Sometimes, a plant needs a little extra water, like when you install a new plant into a bed of established plants. Rather than overwater established plants, attach a Gilmour stationary sprinkler to the end of your hose and let the water run for a deep soak. These small, inexpensive metal sprinklers do an excellent job of providing a temporary drink. Choose the best spray pattern for your garden.
Start with Seeds — winter 2022 issue

Warmer weather is coming in the spring! I’m already thinking about planting tomatoes, eggplants, basil, and all the other yummy warm-season herbs, vegetables, and summer flowers that my family loves.

So often, people ask me how early they can start summer seeds, when to plant seedlings, which are best to start in containers, and which are better planted directly into the ground or raised beds.

All are excellent questions.

Tips for growing vegetables in the warm versus cool months:

  • Vegetables whose “fruits” we eat (the part of the plant that contains seeds), we grow in the warmer months (late March through mid-October). This category includes tomatoes, peppers, eggplants, cucumbers, squash, melons, pumpkin, and their relatives. While you may think of the edible parts as vegetables, botanically, any part of a plant that makes seeds is a fruit.
  • Plants whose leaves, stems, and/or buds we eat, grow in the cooler months (late October through early March). This group includes lettuce, spinach, broccoli, cabbage, kale, Brussels sprouts, onions, etc.
  • Root vegetables vary. We grow carrots and beets year-round. Radishes and turnips prefer to grow in the cool season. Potatoes grow when the soil is warm.

How to start warm-season vegetable, flower, and herb seeds:

Plant carrot and beet seeds directly into the ground or into raised beds any month of the year. “Seed potatoes” appear in the nurseries as early as January.

Between March and June, start warm-season vegetable, flower, and herb seeds in containers, indoors, or in the greenhouse. It takes just six to eight weeks for seedlings to grow large enough to survive the transplant.

By mid-April, the soil is warm enough for transplants to take off. When you plant seedlings earlier, the soil is too cold for them to grow. While they sit and wait for the soil to warm, those seedlings can succumb to molds or fungi, or be eaten by hungry critters.

If you are new to San Diego or looking for gardening information online, don’t be confused by this approach. Our climate and our soils are unique, so the way we garden is entirely different from anywhere outside of Southern California.

Plan now:

Buy seeds. Assemble your seed-starting supplies: seed-starting mix (NOT POTTING SOIL), containers, a seedling heat mat calibrated to 70 degrees (NOT a heating pad, nor a waterbed heater), seedling fertilizer, containers, etc.

Find a sunny window where your seedlings can sit from the time you plant until they are big enough to transplant outside. If your garden is frost-free, put seedlings outside during the day, too. That’s a good way to prepare them for life outdoors.

Prepare your garden beds. If you planted a winter cover crop, turn it over (literally) six weeks before you intend to plant your summer seedlings. Add compost and worm castings to existing raised beds – the ideal way to grow vegetables in our climate. If you don’t yet have raised beds, make or buy some now. I really like the prefab Vegepod (https://bit.ly/2NJpBN0) and Vego Garden beds (https://bit.ly/33XWmlh).

If you garden in containers, refresh the soil there too. Make sure the containers are large enough to accommodate individual plants. A single tomato plant can grow 4 feet across and more than 6 feet tall. Its roots will be nearly as large as the branches and leaves, so plant it into a big enough container.

Some people like to grow vegetables in fabric pots or “grow bags.” In our arid climate, fabric pots dry out quickly, so add a drip-irrigation system or place them near a hose bib and set them in a kiddie pool to make watering easier.

If this all sounds overwhelming, you can sign up for my annual Easy Seed Starting Workshop online or in-person + online. Learn about starting these plants from seeds, growing them up, and transplanting them to your garden. Add your name to my mailing list at waterwisegardener.com. As soon as registration opens, you’ll get a notification.

Don’t be intimidated. Give yourself the opportunity to experiment and have fun.

Waterwise Herbs to Flavor Your World — fall 2021 issue

Herbs are the spice of life. While we think of herbs and spices as the same thing, they are actually quite different. “Herbs” refer to plants whose leaves flavor foods, while “spices” refer to plants whose seeds, bark, and other parts flavor foods. Lucky for us, many delicious herbs grow easily and need very little irrigation in San Diego area gardens.

Most of these plants are native to the Mediterranean where like here, rainfall is limited to fall through spring, soils are “lean,” and summers are hot and dry.

All the herbs below do best with at least six hours of full, direct sunlight each day and well-draining soil. Irrigate with inline drip irrigation (buried several inches down – or “subsurface” — for the shortest growing groundcovers). If you manage irrigation well and thickly mulch your garden, the water needs of these plants go to nearly zero. Mulch also builds a healthy soil ecosystem to support strong, low-maintenance plants.

Remember that fresh herbs are far more flavorful than dried herbs so you may need to adjust the amounts you cook with.

And, as an added bonus, these plants are beautiful in your garden.

Oregano (Origanum vulgare) – Ancient Greeks believed the goddess Aphrodite created oregano’s spicy scent as a symbol of happiness, so they crowned bridal couples with oregano wreaths. Today, we use this pungent herb in marinara sauce and marinades and vinaigrette salad dressings.

Growing oregano could not be easier. This perennial has small, round, green leaves that form on low growing (shorter than six inches tall) creeping stems that root wherever they touch the ground. So a single plant soon makes a good-sized patch. It also makes oregano a good sharing plant. If a friend has a plant, ask for a piece with roots and you’ll soon have a plant too.

There are countless types of oregano, each with a slightly different flavor profile. Crush a leaf and take in its aroma. If you like it, grow it! Cut sprigs as needed and strip the leaves off to cook with them.

Sage (Salvia officinalis) – Sage is a close relative to oregano but its leaves smell more resinous. While nearly all species of Salvia have fragrant leaves, this is the one most people use to flavor food.

Culinary sages grow as low mounds, reaching a foot tall and a few feet across. The leaves are tongue shaped, and different colors – sage green (yes, that’s how the color got its name), variegated gold and green, purple and green, and more. In spring, spires of purple flowers cover the plants. Regardless of the leaf color, the flavors are about the same, so choose your favorite color and get planting.

Harvest by cutting leaves as needed. Sauté sage leaves in butter as a sauce for butternut squash ravioli. Rub them on lamb and other meats. Add sage to your Thanksgiving stuffing mix.

Garden Thyme/English Thyme (Thymus vulgaris) – There are many kinds of this tiny, evergreen groundcover, each with a slightly different flavor profile. Lemon thyme and lime thyme, for example, are both a little citrusy. Most often, however, recipes that call for thyme refer to the common garden thyme, also known as English thyme.

Culinary thymes grow little more than six inches tall with tiny leaves that pack a flavor punch. I grow thyme in a pot; in the ground, it’s easily overtaken by its larger cousins, oregano and sage.

Harvest by cutting sprigs as needed. Tie the sprigs in bundles using kitchen twine to add to soups and stews.

Bay laurel (Laurus nobilis) ­- Bay laurel is far more than a dried out leaf that sits in a bottle on your pantry shelf. Ancient Greeks wove its branches into wreathes to crown their heroes. Today, this wonderful, aromatic evergreen is a necessary ingredient for marinara, vegetable soup, or chicken Marbella.

Bay grows as a tall, columnar shrub or tree with branches covered in leathery, deep green, leaves 4 to 5 inches long. Plant en masse for a deep green hedge or background. Plant in tall ceramic pots at your garden’s entrance for a note of formality – and to keep your bay small.

To harvest, pick a few leaves from the interior of the plant (so its absence won’t be noticed), rinse off any dust and get cooking!

Rosemary (Rosemarinus officinalis) – Rosemaries grow as woody, upright evergreen shrubs or spreading groundcovers that look gorgeous cascading over a wall or side of a ceramic pot. While they are beautiful, their culinary value comes from the extremely aromatic, resinous oils found in their needlelike foliage. In spring, rosemaries flower soft or deep blue, though some varieties bloom white or pink, and always covered in bees.

Rosemary oil is a famous essential oil used since ancient times for strengthening the memory. It was the emblem of fidelity for lovers; it was a popular decoration at weddings and funerals and its incense perfumed religious ceremonies and magical spells.

In the kitchen, rosemary flavors roasted potatoes, chicken, or olive oil. To harvest, cut a stem with pruning shears. Strip leaves off by running your fingers along the stem from tip to base.

Mexican oregano (Lippia graveolens) – Common names can be confusing and this is a prime example. Mexican oregano and oregano are only very distantly related, but their essential oils give them a similar – though not identical – flavor. And while oregano is native to Mediterranean Europe, Mexican oregano is native to the deserts and chaparrals of Texas, Mexico, and Central America.

In our climate, Mexican oregano is an upright, evergreen shrub that reaches 6 to 8 feet tall. Its branches are loosely covered in bright green leaves. In spring, the branches are tipped in clusters of small white flowers that look like verbena flowers – which puts this plant into the verbena family.

Harvest by cutting back branches – that helps keep Mexican oregano plants from growing too leggy. Strip the leaves off to add to Mexican and Tex-Mex dishes.

Working with the Wizards of Landscape Design — summer 2021 issue

Do any of these sound familiar?

  • Your garden needs a facelift but redoing it yourself is harder than you expected.
  • You bought a home but its landscape is worn out, outdated, or just plain ugly.
  • You’ve bought plant after plant, but your garden just doesn’t look the way you imagine.
  • Your water bill has skyrocketed. Now, every time you see the sprinklers watering the grass, you think, “Do I need a lawn?”
  • You discovered vegetable gardening and want raised beds and fruit trees to grow your fruits and vegetables.

If so, it’s time to call a landscape designer. Professional landscape designers are the wizards of garden design. These wizards transform blah, tired, outdated, obliterated, or thirsty gardens into welcoming, productive, water-wise spaces to bring you joy.

Working with a landscape designer is like working with any professional. The more you understand what they do, how to work with them, and what YOU want, the more successful your project will be.

Landscape designers focus on you, the homeowner. Most start with an in-person, on-site client consultation where they ask about your dream garden. They’ll tour your property to analyze the site while they identify opportunities and challenges.

Before that meeting, do your homework. Take photos of gardens and plants you like, and even those you don’t like. Browse the internet too. Talk with your partner or other decision-makers. You don’t all have to agree, but do know what each other would like.

Remember that your garden should complement your home’s architecture and climate. A Japanese garden, for example, fits a Craftsman-style home beautifully but looks out of place with a Mediterranean home. Similarly, the plants that thrived in your Michigan garden will wither in our heat. Pastels and white flowers fade away in our bright sunlight. A skilled designer will steer you away from plants and styles that don’t work here and towards ones that do.

Develop a realistic target budget. Like remodeling, much more goes into landscaping than you might expect. In addition to design costs, there are installation costs such as labor, demolition, hardscape, plants, soil, mulch, lighting, irrigation, and sometimes permits. Share your project budget with your landscape designer so he or she can adjust the scale of the project; though it is up to the landscape contractor to develop detailed installation costs.

If you live in an HOA, know the design review process, the documentation they require, who it gets submitted to, when to submit it, and how long reviews take.

Tell your designer about any unusual property setbacks, height requirements, issues with neighbors, and so on.

If the landscape is part of a larger remodel, involve the landscape designer in the architectural design. Collaboration between the architect and landscape designer helps ensure that the outdoors integrates with the indoors.

Don’t make the mistake of installing your garden’s hardscape (decks, paths, patios, etc.) before you have a planting plan. The two must be designed as a whole. Doing them separately is a big mistake.

Expect to sign a contract that describes the project, the landscape designer’s work scope, milestones, expectations, and payment schedule. Most designers ask for a deposit as well.

Once your designer begins your project, remember that careful and thoughtful design takes time. More than a week, sometimes several months. Expect some back and forth. Allow space for your designer’s creative process. That’s why you hired them.

Once the design is complete, it’s time to get on the landscape contractor’s schedule. Work only with licensed and insured landscape contractors. You may have a gardener you’ve worked with for a long time whom you trust, but their skill level won’t come near that of a licensed landscape contractor. And should things go wrong (!) you’ll have no recourse unless you work with a licensed landscape contractor.

Don’t wait until the last minute to start your project. The best designers book many months ahead. In fact, the demand for landscape designers skyrocketed during the pandemic. Many are booking more than a year out. Landscape contractors book out far ahead of time as well. So, if you have a wedding coming up or another timeline in mind, plan far in advance so you won’t be disappointed.

Finally, expect your landscape designer to stay involved through installation. They’ll answer the contractor’s questions and participate in on-site decision-making. Some landscape designers purchase and place the plants for their designs as well. Keeping the designer involved is the best way to be sure you get the design you paid for.

Once the garden is complete, stand back and appreciate all the hard work and all the hard workers – including you – who made that garden come to life. Enjoy!

Common Citrus Problems — spring 2021 issue

Are your citrus tree leaves covered in black stuff? Do the stems and leaves have white fluffy spots? Are there hard oval bumps on the stems and branches? Or tiny black or white specks on the leaves? Or a white cloud that emerges from the leaves when you touch them?

What are they?

All of these are common with citrus. The black stuff is black sooty mold. White fluffy spots are mealybugs. Hard bumps are scale insects, while tiny black or white specks are aphids. The white cloud is whitefly.

Where do they come from?

Aphids, scale, and mealybugs are “farmed” by ants. These bugs suck sugary sap from the plants and exude sugary droplets – called “honeydew” – from their rear ends. Ants collect the honeydew to feed their young. Ants move the bugs from plant to plant to ensure an ongoing supply of honeydew.

Black sooty mold forms in the honeydew that inevitably drips onto leaves. Whiteflies are ubiquitous and from time to time, when conditions are just right, their populations explode.

What to do about them?

None of these pests will kill your citrus but they can weaken the trees and leave them vulnerable to other pests.

Controlling ants is key to controlling aphids, scale, mealybugs, and black sooty mold. Before you get out the big guns, however, start with the least toxic and mildest approach.

Look for a trail of ants heading up and down the trunk. Once you find them, apply sticky stuff like Tanglefoot® around the trunk of the tree. When ants get caught in the Tanglefoot®, it interrupts their “highway.” Don’t just slather it onto the trunk. Instead, make a band of duct tape or a similar material around the trunk, then smear Tanglefoot® onto the duct tape. Wear disposable gloves as this is messy! Replace the band every month or two so it doesn’t lose its effectiveness. Also, if left on too long, duct tape can constrict the growth of the tree.

At the same time, set out boric acid-based ant traps like the Terro® brand or the KM Ant Pro® bait station. Ants are attracted to these boric acid-based baits, which they take back to the nest. Boric acid destroys the nest.

This one-two punch should go a long way towards controlling ants. Once the ants are gone, natural mealybug and scale predators usually keep their populations under control. If they are still present after a month or so, spray the leaves and branches with insecticidal soap (NEVER DISHSOAP) or light horticultural oil (NOT NEEM). Always follow label instructions.

Next, use a sharp blast of water to clean the leaves of black sooty mold, and to kill aphids and whiteflies.

Normally, whiteflies are kept under control by natural predators, but from time to time, their populations explode. When that happens, spray leaves – especially the undersides – once a week for a month or two. I use a small hose attachment called a Bug Blaster ™, which creates a high-pressure blast in 360 degrees. The pressure of the water and the fall to the ground kill the soft-bodied aphids and the whiteflies, especially their eggs which are attached to the undersides of leaves.

Enjoy your citrus and their bloom, which should smell like heaven about now!

Mixed Fruit in Your Garden — winter 2021 issue

If you would like to add fruit trees to your garden, this is the ideal time of year to do so.

In early January, fruit tree growers delivered bare-root trees to local nurseries. The young, dormant trees bearing fruits like peaches, plums, apples, persimmons, pluots, figs, and others, look like a stick with a wad of roots at the bottom. Since the trees are in the plant equivalent of hibernation, bare-root trees experience little, if any, transplant shock. In spring, they will leaf out like normal. Also, bare root is the most inexpensive way to buy these fruit trees.

Most years, winter is a little too cold to plant subtropical evergreen fruit trees like citrus, guava, and avocado. But this winter has been warmer than usual, and gardeners are planting these trees without problem.

Here are some tips to plant fruit trees now and to do it right. However, there is no “one size fits all” when growing fruit trees, many gardeners instinctively group and plant their fruit trees together. Different types of fruit trees have different needs for soils, light, and especially amounts and frequencies of irrigation. Why is that? Well, these fruits originate in many different regions of the world. For example, apples originated in Central Asia, especially in eastern Turkey and southwest Asia Minor. Peaches are from northwest China, avocados from Mexico, olives from the Mediterranean, figs from Western Asia, persimmons from China, Oranges from China and India, and kumquats from China. Mangos originate in Eastern India and Burma, while pineapple guavas are from South America.

Get the picture? These plants come from all different climates and habitats, so we cannot expect to treat them all the same way. Instead, they need to be grouped according to their cultural needs, especially according to their irrigation needs. Here is how I recommend grouping them:

Group 1 – Deciduous Trees: Deciduous stone fruits, pears, apples, almonds, and persimmons. These trees need regular, deep irrigation from the time new buds appear on the branches until leaves start to drop in Autumn. In winter, when branches are bare and there is regular rainfall, trees need no irrigation. When winter is dry, they need deep water only once a month or twice a month, depending on where your garden is and the kind of soil the trees are planted in.

Group 2 – Citrus Trees: All citruses are evergreen, meaning that leaves cover their branches year-round. These trees need regular, deep irrigation, once every week or two, year-round. In winter, irrigate less often than in hot summer months.

Group 3 – Thirsty Trees: Avocados and mangos are the thirstiest fruit trees. They require regular, deep irrigation year-round, at least once a week – less often for those planted in clay soil.

Group 4 – Dry Trees: Figs and pomegranates are among the driest growing fruit trees. Even abandoned fig and pomegranate trees make fruit, though they produce far more when watered deeply at least once every few weeks when branches are covered in leaves. Don’t water when branches are bare.

Group 5 – Low Water-Use Trees: Pineapple guavas, tropical guavas, loquats are evergreen but surprisingly use low water. Water deeply year-round, primarily in the warm months. In winter, water only in long, dry spells.

Plant all groups of these trees into native soil – no soil amendments. Irrigate with in-line drip tubing arranged in concentric circles on the soil surface and around the base of each tree. Space the circles about a foot apart, starting about 10 inches away from the trunk and extending about a foot past the widest branches.

Fruit trees, especially citrus and avocado, have a significant root mass in the upper foot or two of soil. That is why it is important to irrigate from the soil surface down to the roots. Do not use bubblers, deep root watering, vertical PVC pipes, and so on. They are NOT suited for fruit trees.

Cover drip irrigation lines and the entire planting bed in a 3- to 4-inch-thick layer of mulch. Keep the mulch at least 6 inches away from the trunk. Mulch against trunks keeps them damp and vulnerable to pests and diseases. But that’s a discussion for another day!

To see how bare-root fruit trees are bred, grown, and harvested, please watch “From Fruits to Nuts,” an episode of A Growing Passion at agrowingpassion.com/episode-601-from-fruit-to-nuts.

A Soil Saga — fall 2020 issue

Animal, vegetable, or mineral?” is a question that kicks off every game of “20 questions.” In the garden however, animal, vegetable, and mineral mean something totally different. These are the main building blocks of soil – along with air, water, and microbes.

Soil’s mineral components come from different kinds of rock. The particles that make up soil are clay, sand, and silt. The spaces between particles fill with water when it rains and when we irrigate. Air replaces the water as it is depleted or drained.

Clay particles are very small and shaped regular, packing together tightly. Sand particles are large and shaped irregular, leaving lots of empty spaces between particles. Silt particles are in-between sizes.

The larger spaces between sand particles allow water to move through quickly, while the tiny spaces make it difficult for water to penetrate clay soils. Once there, clay holds moisture for a very long time.

Oxygen (from the air) is critical for healthy plant roots. Water from the soil moves into the roots and up through the plant, where it is used in photosynthesis — the plant process of making energy from water, sunlight, and carbon dioxide.

Mineral, water, and air comprise 95 percent of soil. Five percent of soil is “organic matter” that comes from decomposed animals and plants (the “vegetables”). As animals and plants die and decompose, they release nitrogen, phosphorus, and other critical elements into the soil.

The last component of soil makes up less than half percent by volume but is critical. The “soil food web” is the living component of soil. It is made up of beneficial bacteria and other microscopic organisms such as fungi and protozoa. Earthworms, sowbugs, millipedes, and other tiny critters are also part of the soil food web. They comprise an entire universe of creation, consumption, and decomposition happening underground. Soil food web organisms digest organic matter and release nutrients into the soil,

where roots recycle them back into plants.

Organic matter also absorbs and holds water, which helps plants survive drought. In fact, if you can increase the organic matter in an acre of soil by just one percent, that soil can hold 25,000 more gallons of water. That is a pretty good reason to mulch!

Most soil food web organisms live in the top few inches, where they feed on organic matter. They are not all mixed up together, however. Each component has its sweet spot, with the perfect complement of food, temperature, moisture, and so on. Mixing those very distinct layers by tilling or turning the soil destroys the soil food web. Tilling compacts the soil too, so if you learned to garden with a rototiller or a spading fork, it is time to retire them.

Best Soil for Your Garden or Best Plants for Garden’s Soil

Drought-tolerant plants – whether trees, shrubs, succulents, etc. – tend to come from regions where soils are much like our local soils. That is one of the reasons these plants grow so well in local gardens. Grow them in native soil; do not amend planting holes. Use organic (plant-based) mulch for non-succulent plants. Use rock mulch for succulent plants.

Vegetables – Most vegetables require soils that are high in organic matter, so grow them in raised beds filled with custom soil mixes, typically 60 percent mineral and 40 percent organic matter. Layer on lots of compost and add worm castings before you plant. Add vegetable fertilizer and mulch the beds with a thick layer of straw (not hay). The straw eventually breaks down into organic matter, too.

Plants native to high rainfall, acid soil, and soils high in organic matter struggle when planted in local soils. If you absolutely cannot live without hydrangea, gardenia, azalea, etc., grow these plants in pots. You can simulate their native growing conditions with acidic potting soil that is high in organic matter, acidic fertilizer, and extra water – all more doable in a container.

Six Ways to Prepare Your Garden for Climate Change — summer 2020 issue

The coronavirus quarantine has sent many of us into our gardens for sanctuary, escape, enjoyment, and new beginnings as well as to grow food and feed your family. If you are a longtime gardener, this is a great time to prepare your garden for climate change. If you are brand new to gardening, get things started with climate change in mind.

What can we expect from climate change? You have probably heard climate scientists talk about warmer temperatures, but there is much more to climate change.

Rainfall overall may not change but the rainfall pattern will. Rainstorms will not be as frequent, so we will have longer dry periods in between. When the rains do arrive, they will be far more intense. We have already received hints of that. Do you remember the rains we had back in mid-April? My home weather station recorded more than 9 inches of rain in a week and 4.5 inches of rain on one day. That one day’s rainfall was more rain than in all of 2018!

How can you prepare your garden for heat, intense rainfall, and longer dry periods?

  • Plant water-wise plants. They require little irrigation and have a better chance of surviving the long, hot, dry periods between winter rains. Our native plants, succulents, plants from other Mediterranean climate regions of the world, and plants from dry regions of Baja California, Mexico, are the best choices.
  • Upgrade your garden’s irrigation to in-line drip. In those long, dry periods, ornamental plants will likely need watering. In-line drip irrigation (not point-source irrigation, which involves individual emitters at each plant) is the most efficient and effective irrigation and is very low maintenance. This kind of drip irrigation wets the entire root zone, so there is no need to add emitters over time. Run in-line drip irrigation for an hour or more each time, but not very often. Water-wise plants need the soil to dry out in between watering.
  • Install a rainwater collection system. Every square foot of your roof collects 0.6 gallons of water per inch of rainfall. That translates to 1,200 gallons of water for a 2,000 square-foot roof during a 1-inch rainfall. Collect that water in a cistern or tote. Then use it to water your garden in dry periods.
  • Create dips and swales to capture rainfall on your property. In the old days, the goal was to direct water off your property as soon as possible. Now, the goal is to keep as much water on site as possible. Create swales, dry streambeds, dips, and depressions in your landscape. In these places, water can collect, sit, and sink into the soil slowly over time, making it available to plant roots between rainstorms.
  • Spread a 3- or 4-inch-thick layer of mulch. As wood-based mulches break down, they support the important soil microbes that move water and nutrients to the plants’ roots. Improved soil texture is a mulch byproduct, as is the soil’s ability to soak up and hold water like a sponge. A layer of wood-based mulch or rock mulch insulates the soil to hold in moisture between rainstorms or between watering. In a rainstorm, mulch also helps slow erosion by buffering the impact of raindrops hitting the soil. Just remember to leave some bare dirt somewhere in your garden (at least 5-by-5 inches) for bumblebees and other ground-dwelling native bees. They seldom sting and are very important pollinators.
  • Plant trees. Climate change is largely the result of increased carbon dioxide in the atmosphere. Trees capture and store that carbon dioxide; their shade cools our homes while the water that trees release cools the atmosphere. Trees help stem soil erosion, filter particulates and pollutants from the air, and create the oxygen we breathe. The best time to plant a tree was yesterday. The second-best time is today. Let’s plant trees!
Plants to Stay Home With — spring 2020 issue

It is hard to stay home. It is hard to be away from friends and family, school, work, and routine. Yet this time can also be an opportunity to rethink what home is and how you live at home; that includes the plants that share your living space.

Indoor plants liven up the indoors. Their soft shapes and textures contrast against hard walls, counters and floors. Plants contribute earth colors like green, burgundy, and silver, as well as bold colors like red, yellow, orange, and pink. Some houseplants flower indoors; some are fragrant, and all contribute the invisible oxygen that is critical to our lives.

Most plants we grow as houseplants are native to the shady understories of warm, tropical regions of the world. They are naturally adapted to the lower light and warmer temperature conditions inside our homes. Still, like outdoor plants, indoor plants all have different water needs. Plants like prayer plants (Calathea) and African violets, need to be consistently damp.

Then, there is a large group of houseplants that originate in tropical monsoon regions of the world. According to houseplant grower and breeder Jim Booman of Booman Floral in north San Diego County, these plants are adapted to alternating wet and dry periods, which is the way most of us treat houseplants. Booman grows house plants professionally and for pleasure.

House plants are best grown in plastic or ceramic pots. These materials protect roots from desiccating in the cold months when heating systems dry out the air in our homes. Plastic pots are lightweight too, so they are easy to rearrange.

For the potting mix, look for one that is half perlite, pumice, or other “inorganic” material. These large, irregular shaped particles create large pore spaces for water to drain through easily. The other half of an ideal potting mix is compost, peat, coconut coir or other “organic” material that holds onto water. The balance of organic and inorganic medium both wets easily and drains quickly. That way, roots get the water they need, but do not get waterlogged. Dolomitic lime helps buffer the pH, which is helpful since our region’s water is high in salts.

Add slow-release fertilizer with a nutrient ratio of 15-9-12 into the potting mix. Reapply according to label directions. Then top the pot with a half-inch layer of rounded gravel, marbles, or other inert material. That helps hold in moisture. The mulch also keeps out pesky fungus gnats and curious house cats. Booman cautions against letting a pot sit in a water-filled saucer. Roots that are constantly wet eventually rot. Instead, put rocks in the saucer and set the pot on top of the rocks, out of the water.

When should you water? With these plants stick your finger a few inches down into the potting mix. When it feels dry, it is time to water. Always water pots from the top and for long enough that water runs out the hole in the bottom. That flushes salts through the potting mix and away from roots. If you water just a little bit at a time or mist your plants, you will eventually see a layer of a white crust on the top of the potting mix or the pot. That is salt buildup from the salts that are naturally in our water and it is not good for plants.

Do not be overwhelmed. Growing houseplants is pretty straightforward, even if you lose a few along the way. It has happened to the best of us. Here is a list of houseplants that do not require frequent watering, courtesy of Jim Booman:

  • Dracaena marginata
  • Wax plant (Hoya carnosa)
  • Snake plant (Sansevieria)
  • Philodendron
  • Chinese evergreen (Aglaonema)
  • Ficus
  • Lipstick plant (Aeschynanthus)
Post-Holiday Poinsettia Practices — winter 2020 issue

The holidays are past, and all the decorations put away. What will you do with your poinsettias? Plant them, of course!

Poinsettias’ botanical name is Euphorbia pulcherrima. They are native to tropical forests of Mexico and Central America where they grow ten or twelve feet tall and wide. What look like poinsettia flowers are actually bright colored bracts. The true flowers are tiny, yellow, and sit in the very center of the bracts. The bracts, though, are what make poinsettias so beautiful, and are also what breeders tinker with to create different colors and patterns.

While the wild plants have been tamed somewhat, potted poinsettias are not intended to be houseplants long term. So, keeping potted poinsettias going through the holidays can be a challenge. Your poinsettias will do best in a spot with bright light, where temperatures stay around 65 degrees day and night.

Drainage is critical, in fact, most poinsettias succumb to overwatering – they literally drown. So, remove the fancy foil wrapper as soon as you bring the plant into your house. If you put a plate or bowl beneath the pot to catch excess water, prop the pot up on gravel or on pot feet so the poinsettia does not sit in water. When you water, take the pot to the sink and let the water run into it slowly, until it saturates the soil and starts to drip out the bottom. Wait for the surface to dry out before watering again.

Once the holidays are over, do not throw your poinsettias away; plant them in your garden instead. If you live along the coast, plant just after the New Year. Inland, keep poinsettias indoors in their pots after the last frost in spring, then plant.

Your poinsettias will bloom again, in the ground, if they are planted in a spot that gets total nighttime darkness from September to December. How much light they get during the day is not nearly as important as the darkness they get overnight. If there is a security light nearby or a streetlight, a bright window, or just twinkly lights, the plants will grow but the showy bracts will stay green, rather than turn red or pink or even gold.

Plant your poinsettias in soil that drains well, so the roots do not stay wet – just like in pot. Do not be surprised if they drop all their leaves right after you plant them. Be patient while they recover from transplant shock.

Once the days warm up past 60 degrees, your poinsettias will sprout new growth. At that point, give them some all-purpose organic fertilizer and continue to fertilize through the growing season, following the directions on the label.

If you like big, rangy poinsettias, do not bother pruning. But if you prefer a more compact, bushier plant, prune according to the holidays. Prune the branches back by as much as half on Memorial Day. Do the same thing on the Fourth of July and again on Labor Day. Shape the plant as you prune. New flower buds start to form after Labor Day, so do not prune them again or you will cut off the buds.

By the way, poinsettias were long thought to be toxic, but that has proven to be an urban myth. Like other members of the Euphorbia family, they do have a white milky sap that can irritate skin and damage eyes. That said, as you enjoy your potted poinsettia on the dining room table, it is best to wash your hands if a branch breaks off and the white sap drips onto your skin.

And if you already threw your poinsettias away, at least you have an idea for this year’s holiday season!

Tree Threats Update — fall 2019 issue

Our region’s precious trees are still under attack, threatened by various “bad guys.” Here’s an update from last year’s report.

Shot Hole Borer Beetle
Oaks, willows, palo verde, and California sycamore are just a few of the trees susceptible to infestation by shot hole borers, which continue to spread across the region, according to Beatriz Nobua –Behrmann Urban Forestry Advisor for UC Cooperative Extension. According to Nobua –Behrmann, each beetle bores a tiny hole into a tree’s bark and inserts a bit of fungus. The beetle actually eats the fungus, not the tree, but while a tree might tolerate a small number of beetles, but as the population grows, all those holes eventually kill the tree. By the time you notice that a tree is dying, it could be home to thousands of beetles. Once it dies, each of those beetles (and their offspring) spread out to find new trees to infest.

The best shot hole borer defense is a good offense. Check your trees for tiny holes in the bark, stained bark, gum on the bark, and so on. Mild infestations, Nobua-Behrmann says, can be treated with sprays or tree injections.

One caution: Since shot hole borers can find their way into your garden in firewood and in freshly chipped wood mulch. Nobua-Behrmann recommends that all firewood be kiln dried or properly solarized (heated by the sun’s rays) before you bring it onto your property. Only accept any woodchips (aka “arborist chips”) that are smaller than one inch across. For information about the trees most susceptible to shot hole borers, how to recognize an infestation, and what to do if you find shot hole borers in your trees, visit ucanr.edu/sites/pshb.

South American Palm Weevil
Have you ever seen a Canary Island palm (Phoenix canariensis) whose fronds flop backwards? Collapsed fronds are a sure sign of the deadly South American palm weevil. Other signs are yellowing fronds, holes, tunnels, and frass at the base of fronds. Once infected, a palm becomes a weevil breeding ground. The black, inch and a half long weevils can fly up to 15 miles in a day. They can also travel from palm to palm on poorly cleaned pruning shears, saws, and other tools.

As soon as you see the oddly floppy fronds, It is important to cut down infested palms as soon as you see the oddly floppy fronds, and don’t hire the guy around the corner to do the work unless he or she is a certified arborist and disinfects their tools as they work.

Please don’t move live palms out of infested areas — weevils can move with them. If you suspect that South American palm weevils are in your area, you can trap them using a pheromone-baited bucket trap. Directions are at cisr.ucr.edu/pdf/palm-weevil-bucket-trap.pdf.

To learn more, attend the September 4th meeting on palm weevil management put on by University of California Cooperative Extension in Escondido. Contact Sonia Rios sirios2@ucanr.educreate new email for information.

To learn more about this pest and to report collapsing palms, visit cisr.ucr.edu/palmarum.html.

Citrus Green Disease (HLB)
Experts say it is just a matter of time until deadly citrus greening disease (HLB) reaches San Diego County. It is already infecting orange, lemon and other citrus trees in LA, Orange, and Riverside Counties. The USDA describes it as “one of the most serious citrus diseases in the world.”

Citrus greening is caused by a bacterium that is carried from tree to tree by the tiny Asian citrus psyllid (ACP).

HLB bacteria interferes with the tree’s ability to move nutrients. Leaves on infected plants develop irregular yellow splotches or mottling (yellowing from nutrient deficiencies are have more distinctly even patterns). Fruits stay small, grow lopsided, and taste bitter. Some fruits remain partially green even when ripe. There is no cure.

ACP is in our region, but so far, none of the local psyllids are infected with the deadly HLB bacteria, thanks to an aggressive program by the California Department of Food and Agriculture (CDFA) for releasing tiny parasitic wasps that kill Asian citrus psyllids.

In addition, there is an HLB quarantine that prohibits the movement of citrus fruits, leaves, and trees out of regions of Orange and LA counties. Please, do your part to keep citrus greening from coming into San Diego County by following the quarantine guidelines posted at cdfa.ca.gov/plant/hlb/regulation.html.

If you see or suspect that a tree has HLB, report it at californiacitrusthreat.org.

WaterWise Plants for Your Garden — summer 2019 issue

If you’ve visited or lived in the East, Midwest, Pacific Northwest, or any other temperate climate region of the world, you may have noticed how green those regions look. Big trees and shrubs, covered in large, green leaves, thrive on warm summer rains. When winter’s cold arrives, the trees and shrubs drop their leaves and go into dormancy — a kind of suspended animation — while the plants wait for spring’s warmth to return.

Our region is not green. It is bright and sunny, with scrub-covered hills that are olive green from fall through spring, then brown through summer. They respond to our unique Mediterranean climate pattern. Rain falls during mild cool temperatures of autumn, winter, and early spring. There’s no rain during summer’s dry heat, which is nice for people, but challenging for plants.

Big green trees and shrubs are rare in deserts, too. Some rain falls in winter, but the biggest rainfall occurs during muggy summer monsoons. Deserts get extremely hot, with little rainfall overall, and — other than during monsoon season — the dry air literally pulls moisture from plant leaves.

Plants native to these dry regions have evolved similar survival strategies for extreme heat and limited water. Many native plants go dormant in the heat. Their leaves drop, and branches stay bare until the cool temperatures of fall when new leaves sprout, and plants resume their growth.

Small leaves and narrow leaves are drought strategies, too. Plants lose moisture by evaporation from the surface of their leaves. Larger leaves, with more surface area, lose the most water. Smaller and narrower leaves have less surface area, so they lose less water to the atmosphere.

While we love the feeling of fuzzy leaves, that isn’t why they are covered with fuzz. For plants, that layer of fine hairs is a vapor barrier that slows down water evaporation from leaf surfaces. The hairs shade the leaf from blistering sunlight, too, and their silver color helps deflects sunlight. All are strategies for surviving heat and drought.

Leaves that don’t contain much water, don’t have much water to lose. Some dry-climate plants evolve leaves that are leathery or high in oils, rather than fleshy and water-filled.

Succulence is an obvious drought strategy. In the rainy season, succulent plants absorb water and store it in their stems, roots, and leaves. In the dry season, they use up that moisture to survive.

Next time you see a barrel cactus, notice how beneath the spines, the plant itself is baffled like an accordion. The baffles expand as the plants fill up with water during the rainy season. As the water gets used, the baffles shrink back down.

Even spines have a drought purpose. True, they protect plants from predators, but for some cacti, spines harvest dew from the cooler evening and early morning air, then direct it right into the plant or to the roots.

All plant leaves are covered in a thin layer of wax to keep them hydrated for a longer period. For some hot climate plants, the protective wax layer is so thick that it comes off when you rub the leaf.

These adaptations make for gardens that look entirely different from big, broad-leaved temperate gardens, yet are no less attractive. So, next time you are looking for plants that will thrive in your garden with little or no irrigation, look for these features:

  • Silver leaves
  • Succulence
  • Fuzzy leaves
  • Waxy leaves
  • Leathery leaves
  • Oily leaves
  • Small leaves
  • Narrow leaves
  • Spines

These characteristics are rules of thumb since, for example, silver leaved plants are native to many different climates. So, do your homework. Research plants to find those best suited to our waterwise gardens. Then, then come up with a plan before you go shopping. That’s the best part, of course!

Plant a Tree, or Two… — winter 2019 issue

Climate change is a big issue that overwhelms most of us. We are all part of the problem, but what can we do to be part of the solution? There’s no question that as individuals and as a society, we need to reduce carbon dioxide (CO2) gas emissions primarily by reducing the amount of fossil fuels we burn. To do that, we need to drive less and switch to fuel-efficient vehicles, use solar power in place of electricity made by burning fossil fuels, make buildings more energy efficient, stop deforestation, use less water, and so on.

There’s one additional thing we CAN do — we can plant trees.

Have you ever heard forests described as the “lungs of the earth?” Trees — and plants, including marine plants, — create the oxygen we breathe from sunlight, water, and CO2. Through the process of photosynthesis, water and CO2 become the tree, which includes —the wood, the leaves, and the roots. The process is referred to as “sequestering” CO2. As long as the CO2 remains bound up in the tree, it stays out of the atmosphere. Once the tree is cut down, it decays, and in the process, releases CO2 back into the atmosphere. So the more actively trees growing on earth, the more CO2 is removed from the atmosphere.

In fact, a single tree can absorb up to 48 pounds of CO2 per year, and sequester a ton of CO2 by the time the tree reaches its 40th birthday.

What trees should you plant? The best trees for sequestering CO2 are big trees with big, green leaves. In rainier climates, that describes most of the trees. In San Diego County, trees native and those best adapted to our area tend to have smallish or narrow leaves. Still, planting any kind of tree helps.

Deciduous trees (those that lose their leaves in winter) planted on the south and west sides of your home shade your house to cool it in summer so you use less air conditioning. In winter, after the leaves fall, sunlight penetrating through the branches warms the house, thus reduces your need to run the heater. Not using your heater or air conditioner saves money, conserves energy, and reduces the CO2 emissions from creating that energy.

Shade over concrete surfaces keeps the concrete cool, while planting a tree or large shrub to shade an air conditioner helps the unit run up to 10 percent more efficiently, which reduces its energy use.

In urban communities, properties might be too small for big trees, but several smaller trees can add up to the carbon sequestration job that a big tree would do. Choose a tree that is drought tolerant too. Consider planting Mexican redbud (Cercis mexicana), crape myrtle (Lagerstroemeria), pineapple guava (Acca sellowiana), fig trees, bay laurel (Laurus nobilis), or citrus trees (not so drought tolerant, but they fruit).

Find places in your neighborhood for bigger trees like our native live oak (Quercus agrifolia), Chinese pistache (Pistacia sinensis), tipu (Tipuana tipu), jacaranda (Jacaranda mimosifolia), or kurrajong (Brachychiton populneus). In addition to sequestering carbon, these trees reduce the heat-island effect to cool the entire community. In a park, trees create welcoming shady spaces, and can do so on a hot summer day, too.

If you live in a rural area with lots of room, please feel free to plant lots of trees. In rural areas, trees offer the same advantages as in urban areas, plus they serve as windbreaks, slow runoff, and erosion to protect the soil, serve as habitat for wild animals and insects, and offer many other ecosystem services. If space is not a problem, plant native live oak along with other natives such as sycamore (Platanus racemosa), Engelmann oak (Quercus engelmannii), and valley oak (Quercus lobata). Add large native shrubs such as toyon (Heteromeles arbutifolia), lemonade berry (Rhus integrifolia), and ‘Ray Hartman’ California lilac (Ceanothus ‘Ray Hartman’).

So this year, please, plant and care for at least two trees. Make it one of your New Year’s resolutions – two trees to cool the planet!

Shrubs for Screens — fall 2018 issue

Evergreen hedges are among the many impressive features of European gardens. Classic English, French, and Italian gardens feature tall shrubs, tightly clipped and trained to divide gardens into individual themed garden rooms. Few people realize that those hedges serve multiple purposes, such as a windbreak, protecting sensitive plants from cold. They even keep out hungry critters.

Here, evergreen hedges are more edging plants, green backgrounds, or devices to hide cars on noisy streets or the neighbors’ trash cans. Hedges are high maintenance. They are typically big shrubs, planted too close together, so they require constant pruning and generous water to look good. That is not a winning strategy for most home gardeners.

Instead, use screening plants, which are evergreen shrubs planted in loose groupings and spaced to accommodate to their natural dimensions. Beautiful, water-wise options include pincushions (Leucospermum) that are Protea family plants from South Africa. Softball-sized flowers that look like giant pincushions compliment their green or gray leaves. Most pincushions flower early each year, and in shades of red, yellow, orange, and pink. Typically, pincushions grow between four to six feet tall and eight feet wide or wider. So three ‘Veldfire’ pincushion plants, for example, can cover a space 24 feet long! Check each variety for its dimensions.

Important: Do not fertilize pincushions. If you are fertilizing the bed where they grow, avoid using phosphorus-containing fertilizers (look for middle letter “P” on the fertilizer label). Pincushions evolved in soils that have less phosphorus than ours have, so fertilizers with phosphorus will kill them.

Another option is Grevillea, Australian shrubs in the Protea family, which are available in every size, from low growing groundcovers to tall trees. Most Grevillea sold in nurseries have narrow leaves and some leaves are more sculpted; others more needle-like. For screening, try Grevillea ‘Long John’ which grows at least 15 feet tall by 15 feet wide and has spider-shaped flowers the color of watermelon. Grevillea ‘Red Hooks’ has toothbrush shaped burgundy flowers and grows eight to 12 feet tall and wide, while Grevillea ‘Peaches and Cream,’ has orange and yellow cone-shaped flowers covering six foot tall by eight foot wide shrubs. Phosphorus fertilizers kill Grevillea as well.

Coast Rosemary (Westringia fruticosa and its hybrids) make nice background shrubs and are adaptable to many garden applications. Coast Rosemary’s common name comes from rosemary-like green, needle-like leaves and small flowers. But the two are entirely different plants from entirely different areas. Rosemary is native to the Mediterranean and Coast Rosemary is native to Australia.

Westringia ‘Wynyabbie Gem’ is one of the largest coast Rosemaries, which at six to eight feet tall and wide, makes an excellent screening plant. Westringia ‘Blue Gem’ grows four to six feet tall by three to four feet wide with tiny lavender blue flowers, while Westringia fruticosa grows four to six feet tall by six to 12 feet wide and blooms white. You can easily hide a chain link fence behind a few Westringia.

Toyon (Heteromeles arbutifolia) is a native California shrub common on hillsides, which easily reach 10 or 12 feet tall and wide. They have thick, leathery, deep green leaves that densely cover branches. In spring, their small white flowers do not attract much attention, but by winter, the flowers turn into bright red berries much beloved by birds. To California’s early developers, the berries were a reminder of holly, which is how Hollywood got its name.

Myrtle (Myrtus communis) is a classic Mediterranean hedge shrub in Europe. Since few of us grow formal gardens, we grow myrtle as a screen. Myrtle grows eight to 12 feet tall and wide. It has small, triangular, deep green leaves (there are green and cream variegated leaf varieties, too). Myrtle’s flowers are hardly noticeable but have a nice perfume. Its crushed leaves release a spicy fragrance.

For the fastest growing and most vigorous plants, always plant the smallest possible size. Choose one gallons over five gallons, five gallons over 15 gallons. Do not plant any of these from containers larger than 15 gallons. Design your plan with plants grouped in odd numbers; three of a kind, five of a kind, etc. Do not mix up different kinds of shrubs or alternate them. Groupings of the same plant are much more effective and much more pleasing to the eye. Space plants just shy of their maximum width, then let them grow to their natural sizes. That is the key to creating an effective, low maintenance screen for your water-wise garden.

Beware the Tree Borers… — summer 2018 issue

Trees and shrubs across the region are under siege. Along every major street and in every neighborhood there are dead trees, browning trees, trees that are stressed and in decline. Much of this can be attributed to drought, whether directly or because drought-weakened trees are susceptible to pests, in particular to tiny beetles known collectively as “borers.”

INVASIVE SHOT HOLE BORER, AKA AMBROSIA BEETLES
These tiny, flying Asian beetles – no bigger than a sesame seed – cause big problems for more than 300 kinds of fruiting and ornamental trees and shrubs throughout the region. According to County of San Diego Entomologist Tracy Ellis, there are several kinds of shot hole borers, all lumped into a group referred to as “ambrosia beetles.”

What they do: Pregnant female beetles burrow through the tree or shrub’s bark and into its sapwood as they carve out tiny tunnels (known as “galleries”) to lay their eggs. Each beetle inoculates her tunnels with spores of a fungus that the developing larvae will feed on once they hatch from the eggs (all other stages of the beetles eat the fungus too). Once the fungal colonies begin to grow, the female returns to lay up to 10 eggs per tunnel. You might expect a female beetle to bore one or two tunnels in a tree; but those females are prolific! They can drill enough tunnels to girdle a plant, even enough to make a tree collapse! In the meantime, the tunnels interfere with the tree’s ability to move water and nutrients through its tissues, which spells death for a tree. And while the fungus is food for the beetles, it too is deadly for the tree. One way or another, the tree’s chances for survival are slim.

What to look for: An infected plant may look like it sprung a leak. Sometimes the plant tries to plug leaks by exuding crystal-like sugars to form, “sugar volcanoes,” large enough for you to see. Infected sycamore trees look as if they were shot with BBs. On some plants, branches develop dry or wet and oily, dark stains at the beetles’ entry points. Wood and leaves can become discolored and entire branches wilt, then die back. Ambrosia beetles infect at least three hundred kinds of trees and shrubs, including avocado, California sycamore, willows, several kinds of oaks, Camellia, Acacia, kentia and king palms, Jacaranda, and many more. Gold Spotted Oak Borers are very similar to ambrosia beetles but only attack oak trees whose trunks are eight inches or more in diameter.

Diagnosis: If you think you have a tree or shrub infected by borers, submit a photo or a sample of the plant to the San Diego County Plant Pathology Laboratory for free diagnosis (see below).

Prevention: Healthy, well-hydrated plants are more resistant to infection, while under-watered or otherwise stressed woody trees and shrubs are more vulnerable.

This is another reason to deep water trees and shrubs, even during drought.

Beetles travel on freshly cut wood so be very careful that any wood you bring onto your property does not have beetles:

  • If you bring in firewood, BE SURE the firewood has been aged (“seasoned”) long enough that the bark is dry and falls off.
  • If you bring in wood chips for mulch or any other reason, BE SURE the woodchips are no larger than an inch across and have dried for several months. BETTER YET, avoid the issue altogether by using aged mulch rather than fresh wood chips.

Treatment: There is no cure for badly infected plants; have them removed by a professional arborist who is trained to work with ambrosia-infected trees. Have the wood chipped to particles no larger than an inch; that appears to kill the borers. Have the entire rootball removed.

Websites to watch:

Weedcloth Revealed — spring 2018 issue

A few years ago, we shot an episode of A Growing Passion about creating waterwise gardens (agrowingpassion.com/episode- 405-lawn-gone-waterwise-gardens).

Among the gardens we showcased was a beautiful Los Angeles garden designed by a good friend. For the shoot, he and I wandered through the garden talking about the sloping lawn it replaced. As we walked, I noticed the mulch sliding off the surface, revealing black fabric weedcloth beneath. “Why weedcloth?” I asked him. “I didn’t want to use it,” he said. “It was a requirement.” The lawn replacement was done under a Los Angeles water-agency rebate and one of the requirements was weedcloth.

I was stunned. All the work and effort that went into this beautiful new garden could be wasted by that one misguided requirement.

“Weed cloth,” “weed barrier,” and “landscape fabric” all describe fabric-like materials sold by the roll. The fabric is laid out over bare soil with the promise of a permanent solution to weed problems. Drip irrigation goes beneath the fabric, which is then pinned down with metal staples. To plant, you cut slits in the weedcloth, dig a hole, and plant the plant. Finally, you cover the weedcloth with mulch.

WHAT’S WRONG WITH WEEDCLOTH?
Sadly, weedcloth is not a long-term solution and in fact, is detrimental to the soil, the plants, and the success of your garden.

True, intact weedcloth can suppress annual weeds from developing short-term, but does not stop Bermuda grass or other creeping weeds. They grow out from the edges, emerge from seams, and pop up through holes that develop in the fabric as it ages and breaks down. Annual weeds sprout through those holes, too.

Weedcloth does not stop weed seeds from blowing into the garden, being dropped by birds, or falling off your shoes or your dog’s coat. Those weeds sprout in the mulch that covers weed cloth.

Irrigation under weed cloth is impossible to monitor. If something breaks or starts to leak, you may not notice for a long time, if ever.

Weedcloth is supposed to be water permeable; which may be the case in regions with torrential downpours, but here, water barely penetrates. Soil beneath weedcloth, then, dries out and hardens. Beneficial organisms that keep plants healthy cannot survive under those conditions. And, since this happens out of sight, most people do not notice the transformation to concrete-hard surface until they remove the weedcloth.

Since weedcloth is a physical barrier, it keeps mulch from doing its most important jobs. As mulch breaks down, it incorporates into the soil. That organic matter supports important microorganisms and beneficial insects that help keep plant roots healthy. Mulch also helps heavy soils drain and helps fast draining soils hold water. But when weed cloth is between mulch and soil, none of this happens. Instead, the mulch dries out to dust, and like in the garden I visited, slips off the weed cloth or blows away. It is unsightly and a huge missed opportunity.

Eventually, garden owners wonder why their plants are growing poorly. When they pull back the mulch, they may even find plant roots growing on top of the landscape fabric, rather than in the soil.

After a year or so, weedcloth breaks down. Shredded black strips emerge from under the mulch, making a big, ugly mess. At that point, it has to be removed and has become a big, costly, labor-intensive project.

JUST USE MULCH
Forget weedcloth. Instead, opt for a 3 or 4-inch-thick layer of organic mulch applied directly onto the surface of the soil. “Organic” mulch, by the way, is mulch made from leaves, clippings, tree branches, etc.

Mulch delivers on the promise of smothering weed seeds. Weeds that sprout from seeds that blow or drop into mulch are easy to pull out, thanks to the loose, chunky nature of organic mulch. Reapply mulch once a year or so.

If your garden is entirely succulents, use inorganic mulch – rocks, decomposed granite, gravel, etc. – also in a 3-inch-thick layer applied directly onto soil, without weedcloth.

There is one situation where weedcloth performs a valuable service. When you build a dry streambed that will always be dry (rather than a bioswale), weedcloth under the smallest gravel helps keep the gravel from sinking into the soil and disappearing.

Beyond that, don’t fall for the false promise of weedcloth. Your garden will thank you.

A Few of my Favorite Flowering Shrubs — winter 2018 issue

In other regions of the country, residents are aching for the long, drab winter to end. As if to hasten its end, they take this time to plan bright displays of annual flowers that mark the transition to spring.

We don’t create those kinds of displays here in the San Diego region. We have flowers and foliage year-round so there’s no need for over-the-top springtime floral indulgence. Instead, we plan gardens to have flowers just about every month. And the best way to do that is with flowering, waterwise shrubs.

These shrubs bloom primarily in the cooler months of spring and fall, with a smattering of winter flowers too. They are tough, drought resistant, and almost bullet proof. Best of all, whether in bloom or out, they are a constant background for spring, summer, fall, and winter flowers.

Here are a few of my favorites for our region:

Sphaeralcea ambigua, desert mallow, is a small, open desert native that grows two-to-four feet tall and wide. Its small, silvery green leaves are ridged and covered in fuzz. In early spring, cuplike flowers cover the branches, typically apricot colored, but sometimes white, pink, or pale purple. There is a selection called ‘Louis Hamilton’ that has watermelon colored flowers. Some years, these plants bloom again after the summer. In early fall, thin out dead branches, then cut the plant back to six inches tall. It will flush with new growth. Occasional new plants sprout to replace old ones that die out. Plant them in the full sun, in well-draining soils and water to establish. After establishment, the plants need little if any irrigation. This plant looks beautiful when combined with a blue-blade agave.

Grevillea ‘Moonlight’ is a surprise from down under. This larger member of the Grevillea family has long, narrow, almost needle-like deep green leaves and grows tall, at least eight-to-12 feet tall, and six-to-eight feet wide. In the cooler months, the branches form long, cone-shaped spidery flower clusters that are a pale butter yellow. Their color shows best when the plant is sited against a sage, terra cotta, or coco brown walls. These flowers are hummingbird magnets. They are also easy-to-grow and waterwise. Do not fertilize.

Abutilon palmeri, Indian mallow, is another desert native. This one contains extensive, soft green, and very fuzzy leaves that grow broad, almost like a maple leaf. Site this plant near a walkway so you can feel the leaves as you walk by. Deep, gold yellow flowers form at the branches tips, mostly in spring and fall, with some present, year round. This shrub grows surprisingly large, at least four feet tall and five feet wide. After most flowers are past, cut the spent flower stalks off. You can also cut the plant back at least by a third. This plant is extremely drought tolerant. Water little if any, once it’s established. Hummingbirds and butterflies are frequent visitors.

Ceanothus, California lilac, are not lilacs but rather a large group of evergreen shrubs native to different regions and habitats up and down the state. Some are the size of small trees (Ceanothus ‘Ray Hartman’ grows to 20 feet tall) and some are low groundcovers (Ceanothus griseus horizontalis ‘Yankee Point’ grows two-to-three feet tall and eight-to-10 feet wide), and all sizes in between. In early spring, these shrubs form rounded clusters of tiny flowers, in shades of white-to-deep indigo blue. If you’re close, you’ll notice the flowers’ fragrance, too. Ceanothus get a bad rap for being short lived in the garden, but that is usually from being planted where they get too much irrigation or are overwatered in general. Instead, water regularly through the first summer to establish, and then only during long dry periods from fall through spring. Water little, if at all, in the summer – that’s Mother Nature’s pattern too! Excellent plant for attracting wildlife to the garden.

Eremophila glabra ‘Kalgoorlie’ is a small, evergreen shrub from Australia, just three feet tall and four-to-six feet wide. It has narrow, ghostly silver green leaves and tubular flowers that are apricot and gold. The spring and summer flowers are subtle, but there are so many that collectively, they make a big impression. Plant in the full sun, well-draining soil, and shear back by a third after the bloom has past. I like to grow this on a slope, under taller flowering shrubs like Grevillea ‘Moonlight’. Both have hummingbird-attracting flowers.

Plant and Tree Watering Basics: Keeping Plants Healthy After Hotter Temperatures — fall 2017 issue

Finally it’s fall! Cool days and cool nights are a huge relief, for both people and plants. It also means it is time to change the way you are watering your garden.

In the hot, dry summer air, plants are under huge water stress. They lose water from their leaves faster than their roots can replace it with water from the soil. That’s why plant leaves can look droopy, especially towards the end of a hot afternoon.

Once the weather cools, and especially when the air is moist, plants don’t have nearly as much water stress. At the same time, the days are shorter and the sun sits lower in the sky. With the limited sunlight for photosynthesis, plant metabolism slows down. And with that, the plants’ water needs decrease.

If you water by hand, notice that it takes longer for soil to dry out now. There’s no reason to water wet soil, so wait longer between watering. I have a large collection of potted plants and in the summer, I water every plant twice a week and sometimes more often. In the winter, the potting soil stays damp longer, so I water just once a week.

If an old-fashioned manual irrigation clock controls your irrigation system it’s time to adjust your clock. Each zone should run less often, but for the same number of minutes as it ran during the summer. If your garden soil is clay, you might be able to water just once every few weeks through fall and not at all in winter, especially when (or if) it rains. If your garden soil is sand, sand drains very quickly so the irrigation needs to run more often, maybe once every week or two – unless it rains.

If your garden’s irrigation is managed by a “smart” controller, the controller is programmed to adjust the irrigation schedule seasonally, based on where your garden is located, the type of soil in your garden, types of plants, and a few other factors. Most systems have mini-weather stations that monitor heat, humidity, and rainfall to determine how often and how long to run each irrigation zone. Like with any other technology, you should check the controller’s log periodically to see how well it is doing its job. Now is a good time to do that check. Notice how often each zone runs and for how long. If the history doesn’t show your system running less often now, look for a button labeled “percent” or “%” and adjust the schedule there.

If it rains, smart controllers shut the system down until the soil dries out. Have you ever cleaned your smart controller’s rain sensor? Dead leaves, dirt and other debris can collect in the sensor and interfere with its operations. Look for your controller’s rain sensors as part of a self-contained unit typically mounted near the irrigation controller and on a high point, like your home’s eaves or roof.

If you are establishing new plants or a whole new garden, the newly installed plants need a little extra water this year, and maybe next year too. Establishing new plants in an existing garden can be a bit tricky since you want the new plants to get enough water, without overwatering everything else. I like to water each new plant with a small hose-end sprinkler set to make a fan only large enough to cover the soil beneath the plant’s canopy. I set the timer on my smartphone for 30 minutes or so.
Once the soil is saturated, I move the sprinkler on to the next new plant.

Establishing an entirely new garden is more straightforward, especially if you have an irrigation controller. Some smart controllers have a setting for establishing new gardens. If yours doesn’t, set the controller to run often enough to keep all the soil damp but not wet. Then, don’t just walk away. You’ll need to monitor the garden and make adjustments to the controller as needed.

And if we are very lucky this winter, Mother Nature will do all the watering for us.

Tree Watering Basics: Keep Trees Healthy After a Drought — summer 2017 issue

It’s nice to get a breather from extreme drought but we live in a water poor region and our gardens – along with our lifestyles – should reflect that daily. We’ve come a long way changing gardens to be lush and green, using plants suited to the region’s water reality.

The focus has been on removing lawns and replacing thirsty plants but in our haste, we’ve not done well by trees. Some people removed trees based on their misperception that trees waste water. Others simply stopped watering trees and expect them to do fine. Neither is the case.

The value of trees
Trees are extremely important in wildlands, rural environments, and urban areas. They provide many “services” that few of us recognize. For example, the carbon dioxide we exhale is the gas trees take in during photosynthesis. And as they photosynthesize, they recharge the air with the oxygen we need to breathe.

Tree roots capture, slow, and clean runoff. Their roots hold water that would otherwise flood our communities.

Tree leaves shade and cool our houses. They also filter the air and capture particulates we would otherwise breathe in. Trees serve as habitat for birds, good bugs, and other important critters.

Trees are one of the most powerful tools in the fight against global warming
Cities and suburbs are hot places thanks to paving, buildings, cars, machinery, air conditioning, reflective surfaces, and so on. But trees and other plants release moisture into the air; a sort of evaporative cooling that makes a huge difference. I recently measured the temperatures of different surfaces in downtown San Diego. When the air was in the upper 60s, the concrete sidewalk was in the 80s, the asphalt street in the 90s, the rubber playground surface was in the 120s and artificial turf was more than 130 degrees (really).

Yet the soil under a shade tree was in the 50s!

Trees serve other important roles too. There’s so much to be said for trees – it’s time we stopped ignoring them, and started caring for them.

Tree watering basics
Trees, like all plants, take up water through their roots. Equally important, trees need to grow deep, drought resistant roots.

Trees don’t belong in lawns. That’s fine in climates where there’s plentiful rainfall and soil stays moist deep into the earth. Here, trees planted in lawn develop shallow roots that take up surface water but not the important, deep, drought-tolerant roots. To encourage those roots, trees need deep, infrequent irrigation.

Newly planted trees
In their first two or three years in the ground, trees should be watered about once a week, with 15 to 20 gallons each time (captured shower water or rainwater are fine). Before you water, stick a finger into the soil, about 4 inches deep. If you feel moisture, it’s not yet time to water. If it is dry, water.

At planting, build a 3 or 4-foot-wide basin around the tree’s trunk. If you have the patience, water from a bucket, adding it to the basin slowly. Alternatively install concentric rings of in-line drip irrigation around the trunk. Set the first ring 8 to 10 inches out from the trunk, add rings every 10 to 12 inches to just past the drip line (that’s the outer edge of the canopy). As the tree matures, the trunk will thicken. Over time, remove the inner irrigation rings and add more to the outer edges, keeping their spacing at 12 inches.

Established trees
After three years most trees are established, which means they’ve developed a pretty deep and extensive root system. Irrigate these trees less often — only once or twice a month — but with more water each time. The goal is to wet the roots 1 or 2 feet deep. This is when in-line drip irrigation is most important. Set rings of in-line drip irrigation a foot or 18 inches out from the trunk, and extend to just past the drip line. For a short term fix, use concentric rings of soaker hose. After a few years, their pores will clog. Recycle the old ones and replace them.

How often to water
You’ll need to experiment to figure out how long to run the irrigation. With clay soil, water moves into the soil slowly and stays a long time. With sandy soils, water moves through quickly and dissipates. Use a soil probe to determine out how deep water penetrates as you irrigate. Use the probe after you irrigate too, to see how long water stays in the soil. When the area around those deep roots to start to dry. That’s when you irrigate again.

Different kinds of trees need more or less water, too. Deciduous fruit trees like peaches and apples need water when they have leaves, flowers, and fruits on them. In winter when it rains, they may not need any irrigation at all. Citrus on the other hand, need irrigation year round. Don’t make the mistake of putting citrus and avocado trees on the same irrigation zone as peaches, plums, figs, or pomegranate. You’ll end up watering those less thirsty trees more than they need just to supply the citrus and avocado.

University of California recently posted directions for assembling your own “Tree Ring Irrigation Contraption” using standard in-line drip irrigation, along with a calculator for figuring out how long to run the water. Find it here tinyurl.com/hlwzeq3.

Mulch
Young or old, fruiting or not, all trees should be mulched. The best mulch is woody mulch applied at least 3 inches thick, starting 6 or 12 inches out from the trunk. Mulch insulates the soil to hold water in and keeps soil cool.

To learn more about the value of trees and caring for trees in urban environments watch A Growing Passion’s recent episode on Urban Forestry, tinyurl.com/ycnhyu48.

Planting Slopes and Hillsides: Gardening at an Angle — winter 2017 issue

Many San Diego subdivisions are cut into hillsides and out of hillsides, thanks to our wacky topography and policy of building on every inch of usable space. That leaves homeowners to deal with pretty challenging slopes and the baffling issue of how to plant a hillside.

Most people think “groundcover” when it comes to a hillside. But have you ever seen a mountain covered in groundcover? Nature doesn’t do that and neither should we.

Slopes and hillsides are simply gardens at an angle. You have to choose the right plants and avoid over irrigating, but it’s not that difficult.

One of the biggest issues is how to keep hillsides from eroding and from washing away. The best plants for the job are ones that make deep roots to stabilize the soil, yet require very little irrigation. Native trees and shrubs are ideal: California lilac, toyon, oak trees, and sugar bush are good examples. Include Romneya coulteri, the giant Matilija poppy. This six foot tall perennial is known as the “fried egg plant” for its round, white crepe papery flower with a yolk-yellow center. Underground, it forms a vast network of creeping roots. California natives also create habitat for birds and other wildlife.

Shrubs and trees from other Mediterranean climates work well too. On garden tours I lead in these regions, I marvel at how similar the native habitats appear to ours, yet are entirely different plants. In Italy, for example, the macchia (also called maquis) is the equivalent of our chaparral. Plants like rockrose (Cistus), cork oaks (Quercus suber), rosemary, carob (Ceratonia siliqua), and bay (Laurus nobilis) grow wild there. All are excellent choices for hillside gardens too.

Plant succulents and other shallow rooted plants around and under these plants, but as accents rather than for structure and stability. Sprinkle in some California poppy seeds and you’ll have a lovely springtime display.

Avoid Eucalyptus and other trees and shrubs with shallow roots and brittle branches. As we see whenever storms hit, these plants are among the first casualties.

Don’t plant ice plant, especially Hottentot fig (Carpobrotus edulis). This spreading succulent is many people’s choice for covering vast slopes. However, the plants grow new succulent blades over top the old dead, brown, blades and stems. Eventually, the mass grows so heavy that it slides, taking the slope down with it. In addition, Hottentot fig is an invasive plant.

A single, uniform planting of one plant across an entire slope is never successful. It is simply impossible to maintain an even, uniform look. Over time, a plant dies here and there, gophers burrow up from below, and weeds blow in. Our eyes focus on the flaws. It simply looks crummy.

How to plant a slope:

  • Choose deep-rooted woody shrubs and trees with low-water needs, suited to your garden’s microclimate. Use trees for structure, shrubs for substance, succulents and spreaders to fill the spaces between.
  • Group plants in sweeps of threes, fives, or sevens to create a beautiful, undulating mosaic. Don’t alternate plants in a hopscotch pattern.
  • Irrigate slopes with in-line drip irrigation. Overhead spray can worsen runoff and erosion. The County of San Diego Landscape Design Manual mandates that any slope greater than 25 percent (one foot elevation change for every four level feet) be irrigated at a precipitation rate of no more than .75 inches per hour. Drip is the most direct way to achieve that slow rate.
  • Top the soil and cover the irrigation with a thick layer of woody mulch.

Just like any other garden!

Feasting Through Fall — fall 2016 issue

It is always a bit sad to pick the last of the summer’s tomatoes, squash, pumpkins and eggplants. These are my favorite vegetables, in part because of their flavors and in part because they are just so beautiful when they ripen red, orange, yellow, and purple. But then, I remind myself about all the wonderful vegetables that are planted now to eat through fall, winter, and early spring.

As a rule of thumb, any plant whose fruits we eat (botanically, anything with seeds is a fruit, so tomatoes, squash, eggplant, pumpkins, and peppers are fruits) need the long, hot months of summer to ripen, so we plant those in early spring for summer picking.

From fall through early spring, we grow and eat leaves (lettuces, spinach, kale, cabbage), stems (leeks, celery, kohlrabi) roots (carrots, beets, radishes), and so on. We eat the developing flower stalks of broccoli and cauliflower.

It’s time, then, to start those fall veggies. Root vegetables like radishes, carrots, turnips, and beets are best planted from seed, directly into your garden bed or container. Whether you grow in the ground or in raised beds (which is the preferred backyard method in our area), dig in plenty of compost first and dampen the soil.

Carrot seeds and other tiny seeds are hard to spread evenly over a garden bed. So try this; mix the seeds with dry construction sand (not playground sand) or dried coffee grounds in a pint-sized yogurt or cottage cheese container, Mix about one-part seeds to four-parts sand or coffee grounds. Then, scatter the seed mixture over the prepared bed.

Sprinkle a very thin layer of soil over the seeds, with seeds this small, if they are planted much deeper, they might not germinate. Press the soil surface gently with a flat board or the heel of your hand – that ensures that seeds and soil fuse together.

Vegetables that are not root vegetables can be planted from seed or as seedlings. Independent nurseries (those that are locally owned) offer a surprising selection of varieties. Some farmer’s market vendors sell seedlings as well.

I like to start my own seedlings in sterilized plastic six packs or four packs saved from past seedling purchases. I also use pint yogurt or cottage cheese containers that I sterilize too. To sterilize, clean the containers first, then soak for about 20 minutes in a solution of one part bleach to nine parts water.

I never start seeds in egg cartons. There’s not room for enough soil and it is very hard to keep cardboard egg cartons from drying out too quickly.

If you are planting seeds into containers, use brand new seed starting mix rather than in potting soil and don’t recycle old seed starting mix. Fill the containers with seed starting mix, then dampen it. Label the containers, then plant the seeds.

After you plant seeds, put the containers outside in spot that gets part day sun and is protected from critters. It is best if they are in a place where you can keep an eye on them too. To water, fill a basin of water with an inch or two of water, then set the containers into the basin. Let them sit until the water wicks to the top, then remove them to drain.

When the seedlings are about six weeks old, they should be large enough to be planted in the garden.

To plant seeds directly in the ground or into a raised bed, read the seed packet for the ideal planting depth and width.

As your vegetables grow, fertilize with organic vegetable food. Mulch them with straw and have fun growing your own cool weather feast.

El Niño Finally Arrived – Now What? — winter 2016 issue

We’ve had our first taste of El Niño rains; four inches in three days! That’s almost half the rainfall we normally see in a year. Fortunately, we prepared ahead of time. The plumber came out a few weeks ago to clear in-ground drains. The tree trimmer lightened the canopies on our largest trees. The rain gutters got cleaned out, too. All were time and money well spent.

Many people ask me how to protect their plants from rains but that’s not really an issue. As I mentioned in a recent radio interview about El Niño, when it rains, plants do a happy dance. Water doesn’t hurt leaves or stems or branches. The risks instead, come from what happens to the water once it hits the ground. Standing water can drown plant roots; plants can be washed away in a mudslide or by fast moving water, or undermined by erosion.

How do you prepare for El Nino rains? Here’s my to-do list:

  • Clean out rain gutters so water doesn’t cascade over the sides and smash the plants below.
  • Redirect downspouts to disperse water into bio-swales. From there, it will slowly percolate into the soil. If you have poor draining clay soils, install rain barrels to save the water, then use it once the garden dries out.
  • Check drains to be sure they work properly. Clear clogs to avoid flooding.
  • Turn over pots, buckets and any other open containers that might collect and hold water long enough for mosquitoes to breed in.
  • If you collect rainwater in open buckets, put a lid on the buckets between downpours.
  • Protect bare slopes from erosion. Install straw wattles horizontally across hillsides. Wattles are essentially mesh tubes filled with straw and staked in place to serve as speed bumps as water runs downhill. By the end of the season, the straw will break down and can be emptied onto the soil. Compost “socks” are similar to wattles but are filled with compost.
  • Manage the water in your rain barrels. Don’t collect water from the first rain. That “first flush” carries chemicals, dust that settles from the air, dirt, bird poop, debris, etc. Let that water go and capture the next rainfall.
  • Renew your garden’s mulch. Organic mulch — that’s mulch made from leaves, bark, wood, etc. — traps water as it falls. That protects soil from erosion and absorbs water like a sponge. Once water percolates into the soil, mulch helps keep it there by slowing evaporation. And, as mulch breaks down, it builds healthy soil to support the plants in your garden.
  • Turn off your irrigation. If we get a long, hot dry spell or Santa Ana winds, you’ll need to water. That’s unlikely to happen more than a time or two between now and the end of March.
  • Use the time between storms to plant. Plant any of our native plants and plants from dry climates of South Africa, Australia, Chile and the Mediterranean coast. Make your plans, do your research, then head to the nursery. Don’t plant right away, however. Let the soil dry for three or four days after a rain. Digging and standing on wet soil compacts it, the opposite of what we want to do.
  • When you do plant, plant directly into unamended soil. Research tells us that plants in “native” soils do better than those in amended soils. It’s OK to toss in a few handfuls of worm castings, but skip the fertilizer and don’t bother with soil amendments.

Remember this year’s rains are to be welcomed, not feared. While they won’t solve the drought, every drop certainly helps. Sadly, the El Niño rains won’t end California’s drought. But if you capture some of that rainfall, you can use it later in the year, after the rains end and the soils dry out. Shop for rain barrels and learn about rainwater harvesting at your local garden center or irrigation store.

Give That Tree a Drink — fall 2015 issue

The weather is finally (and thankfully) cooling as San Diegans await the El Nino rains.

After four long years of drought, even when El Nino arrives, it won’t bring us back to normal. So, we need to pay attention to trees. We’ve been so focused on killing and replacing lawns that we’ve overlooked the fact that trees are suffering.

Beyond beautifying our gardens, trees generate the oxygen we breathe. Trees remove CO2, one of the greenhouse gases, from the air (that’s the process of carbon sequestration). As trees respire, the moisture they release into the atmosphere humidifies it and cools it. Trees hold water in soils and “feed” the microscopic underground flora and fauna that keep soils healthy. Above ground, trees create habitat for wildlife. They shade and cool our homes. Some trees even do us the great favor of making delicious fruits.

It’s hard to see the effects of drought on established trees, according to Robin Rivet, La Mesa resident, certified arborist, and urban forester. A tree can suffer for four or five years before it shows visible symptoms like leaf drop, droopy leaves, or browning leaves.

Rivet says that while we can’t see it, all the landscape trees across San Diego are in crisis and desperate for water, especially those once surrounded by lawns. The most important thing, now, is to water all your garden trees. Yes, water them.

Does that sound like a conflict with watering restrictions? It isn’t. Otay Water District restricts watering times for old-fashioned overhead sprays, which is the worst way to water trees anyway.

Soaker hoses, drip systems, and highly efficient spray heads are not subject to the same runtime limitations, but are limited to running twice a week, between 6 p.m. and 10 a.m. But that’s a great schedule for watering a tree. Rivet recommends using drip irrigation, soaker hoses or seeping hoses placed slightly inside the tree’s drip line (the drip line is the outer edge of the tree’s canopy). Turn the water on in early evening and off in early morning. The goal is to slowly saturate the soil under the tree two or three feet deep. Saturating the soil, irrigates the roots.

How often to water depends on your soil and the tree’s age. Water penetrates through and drains away quickly from sandy soils, so you might deep soak established trees once or twice a month, newly planted trees more often. Water penetrates clay soils slowly and stays a long time, so deep soak only once every two months or less often for established trees in clay soils, more often for newly planted ones.

Rivet suggests using a straightened out wire clothes hanger to determine how deep the water has penetrated. Poke it into the soil as deep as you can, then pull it up and feel the hanger to see how much of it is damp. That tells you how deep the soil is moist. Wait till the hanger is dry most of the way down before watering established trees again, dry only several inches down before watering newly planted trees again.

Once the rains start and hopefully continue, hold back on watering. But if this winter ends up as dry as last winter, the winter before, the winter before that, and the one before that, you’ll be watering all through the season.

Figs Don’t Drink — summer 2015 issue

You might wonder if the drought means the end of fruit trees in our backyards. The answer is “no.” There are many kinds of fruit trees that produce with little, if any, irrigation once trees are established. My top five list includes fig trees.

Figs originated in the hot, dry Middle East. They grow easily here, and there are many varieties to choose from, thanks to their being in cultivation for over eons and by different cultures across the world.

In my garden, I grow the mild flavored, apple sized ‘Long Yellow,’ which has yellow skin and pale flesh. ‘Brown Turkey’ is medium sized fruit with brown skin and very sweet burgundy/brown flesh. ‘Panachee’ (also called ‘Tiger Stripe’) makes small figs, green and yellow striped outside with strawberry colored flesh that tastes sweet and bright.

There are many more fig varieties on the market too.

Once you select a variety, plant your fig tree in the hottest area of your garden, where it will get at least six hours of full, direct sun each day. Figs prefer well-draining soil, so plant into a raised mound if your soil is clay.

Dig the hole so the tree sits at the same height in the ground as it did in its pot; then one and a half or two times as wide as the pot.

Don’t bother amending the planting hole, but do add a few handfuls of worm castings to help jumpstart beneficial soil microbes.

Next, set a gopher basket into the planting hole to protect roots at the base of the tree. If gophers eat the peripheral roots, the tree will likely survive, but if they get the main roots the tree will die. Purchase Gopher baskets in nurseries or make your own from chicken wire (just be sure to wear leather gloves!).

Fill the hole and the container each with water and allow it to drain. Then, remove the tree from the container and rough up the rootball. Gently set the tree into the hole, then backfill tamping soil down and wetting it every few inches.

Finally, make a shallow basin around the trunk of the tree for deep soaking right after planting and every few weeks through the first few months.

At the same time, install in-line drip irrigation (rather than bubblers or individual drip emitters) around the tree trunk. Starting at about eight inches away from the trunk, make concentric loops of irrigation lines, spaced about 12 inches apart. Set the last loop a foot beyond the tree’s canopy.

Figs require no special spraying or pruning. Their soft, white wood is easy to prune and even to shape as espalier. Prune right after harvest, in the short window before next year’s fruits begin to form.

While figs can be fertilized, fertilizers promote vigorous growth that counters the goals of drought tolerance. Instead, spread a three-inch thick layer of mulch over the soil under and around each tree. Leave the soil right around the trunk bare so mulch doesn’t touch the tree.

The cooler months of fall and winter are best planting months. If there is no rain, deep water often enough to keep roots damp (not wet) through the first year or two.

After that, some gardeners can stop watering altogether, depending on the garden’s microclimate. That said, monitor plants, especially in the hot months. If leaves droop a little during the day, that may not be a problem but if they droop first thing in the morning, that plant is water stressed. Deep water it right away.

Figs have two ripening seasons, depending on the variety. Most ripen at the end of summer but a few also have an early crop, called a breba crop, in early summer. Either way, figs ripen only on the tree so don’t to pick them early.

I love eating figs fresh off the tree, but of course they are wonderful as jam, roasted, tarts, and baked in chicken dishes.