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Watch your garden’s water needs as warm, dry conditions settle in

December 4, 2021


Warm, warm, warm, dry, dry. This is our second La Nina year in a row, which means this warm, dry weather will continue at least through early spring. Normally, we’d turn the irrigation off now, but unfortunately, not this year.


Here’s the dilemma: The warm, dry weather means we need to water more often than in a “normal” year. Drought means there’s less water available. What to do? Switch to inline drip irrigation. Inline drip is basically long flexible tubing with emitters embedded inside the lines. Lay it out in a grid on the surface of every garden bed so each bed gets wetted evenly and water penetrates down to the roots. Cover the irrigation and the bed with at least 3 inches of mulch to minimize evaporation. It’s the perfect solution.

Even though the weather is dry, the sun is low in the sky, so plants need water much less often than at the peak of summer.

How long to water? Run your irrigation system, one zone at a time. As each zone finishes. stick your finger all the way down into the soil, as deep as you can. Is it wet all the way down? If not, run the irrigation again. Figure out how long it takes for the water to reach down to the roots. That’s how you figure out the run time for each zone.

Are you watering often enough, or too often? Do the “canary test” to figure out how often to run each zone. As you run each zone, mark the date on your calendar. Then turn the zone off. Watch that area of your garden for the first plant to have droopy leaves (that’s the canary) and check your calendar. Run the water just short of the time it took for the first plant to droop. Use this information to set how often each irrigation zone runs. Don’t expect them all to be the same. So, if it took 12 days for the first plant to droop, run that zone every 11 days. If it drooped after three weeks, run the zone every 20 days. Where the first plant drooped after a week, run that zone every six days, and so on.

Be sure to run your irrigation the day before Santa Ana winds are expected. Saturating the soil protects plants from desiccation.

If you still use overhead spray, it is time to switch to inline drip. Inline drip — not the kind of drip with individual emitters at the end of narrow tubing — is the most efficient and effective irrigation available.

Manage water

Gutters filled with leaves and debris overflow when it rains, beating up the plants below, so clean the gutters now. Compost the debris, or spread it around the garden as mulch.

If you still have water in your rain barrels from last month, use it now. Because it is so dry now, your plants need it.

Rather than collecting water in rain barrels, sculpt your garden soil with dips and swales that capture water so it can absorb into the surrounding soil. Bank water now for long-term withdrawal by your plants’ roots in spring.

Do you have a spot on your property that floods every year? Reconfigure the contours, install a new drain, lay out sandbags, or do whatever else is needed to stop that flood.

While water is precious, don’t let it accumulate in dishes under potted plants, buckets, containers and other places where the constant moisture can drown plant roots or become a mosquito nursery.

When it does rain, stay off the soil for a few days. Wet soil compacts easily, so rather than dig or weed or plant, do chores like repotting plants, cleaning your toolshed and planning for spring.

Prepare for cold

Watch for the winter’s first frost. We don’t get hard frosts, but plants from coast to mountains can suffer frost damage on a cold night.

If your garden gets to freezing or below, protect cold-sensitive plants such as Plumeria, bromeliads and some varieties of succulents, and move them under the eaves (if in pots) or under the dense cover of an evergreen tree. Cover potted or in-ground plants with floating row cover (not plastic). Use clothespins to secure the cover in place.

If a plant is damaged by frost, do not cut off the damaged parts — they protect the rest of the plant from the next freezes. Leave them in place until after the last frost of the year, typically in February or March.

Fruit trees

This is the most important maintenance time for deciduous fruit trees — those that drop their leaves in winter: apples, pears, peaches, plums, pluots, cherries and more.

Between now and the end of January:

Strip leaves off the branches of stone fruits, pears and apples if they don’t fall off on their own. Leaves can be infected with fungus and other pathogens that overwinter. Don’t compost them. Rake them up instead, then send them off in the greenwaste.

Prune deciduous fruit trees, taking care NOT to cut off the fruiting wood. Different kinds of fruit trees form fruits on a different parts of their branches. Apples, for example, grow short spurs along the branches. Those spurs make flowers and fruits. Pomegranates and figs fruit at the end of branches. Pluots fruit along the length of the branch. Know how a tree fruits before you cut.

My favorite pruning guide is “How to Prune Fruit Trees” by R. Sanford Martin. It’s a classic!

After pruning, spray fruit trees to kill overwintering pests and diseases. Spray once, wait two weeks, spray again, wait two weeks and spray a third time.

  • Spray apple and pear trees with mineral-based horticultural oil.
  • Spray stone fruits (peach, nectarine, plum, etc.) with liquid copper to kill the fungus responsible for the dreaded peach leaf curl, alternating with mineral-based horticultural oil to suffocate scale, whiteflies, mealy bugs and other tiny pests that overwinter in the bark.

Every time you spray, coat all branches and trunks, from tips to base. The better the coverage, the more your trees are protected.

Prune ornamentals

Winter is time to prune ornamental trees and shrubs. Hire a certified arborist who will remove weak or dead branches, check for borer infestations, structural integrity and so on. If you don’t have a favorite certified arborist, find one at

If you do the pruning, sharpen your pruning tools first so they make clean, healthy cuts that don’t shred the wood.

Work clean. Disinfect pruning shears, saws, loppers and other cutting tools before and between plants to avoid spreading diseases and pests from one plant to the next. I use spray household disinfectant.

Start pruning by first removing dead branches, weak wood, and crossing branches. Then prune for shape.

Make cuts in the right spot. Follow each branch to where it attaches to the trunk or to the next larger branch. Notice the swelling at the base of the branch? That’s called the branch collar. When you cut, cut up to the branch collar, leaving no stubs behind.

NEVER top a tree. If a tree is too tall, replace it with one (or two or three) that doesn’t grow that tall.

Prune, then spray roses, but not too much. There’s no reason to prune shrub roses down to nubs. The more branches, the more flowers, so let your rose bushes grow large.

Each time you finish pruning, spray your tools again, wipe them dry and lubricate them with mineral oil before storing.

Care for potted plants

It’s poinsettia time! Remove the fancy foil as soon as you get a poinsettia home. Make sure its pot has drainage holes. If it doesn’t, move the plant to a new pot with drainage. Place it in a brightly lit room away from the heater vent and away from a cold window. Water enough to keep the soil damp but not wet. Don’t fertilize until after the holidays.

Monitor potted plants. Feel the potting soil every few days and water before the soil gets too dry. A humidifier can help keep indoor air moist and plants from drying out.

Control pesky little black flies. These fungus gnats are attracted to wet organic matter in the potting soil. They are easy to control without chemicals or sprays if you 1) water less (your plants will be fine) and 2) cover the surface of the potting soil with a ½- to 1-inch-thick layer of small pebbles, aquarium rocks, even marbles. They form a barrier the flies can’t penetrate.

Plant ornamentals

Natives planted now will be ready for next summer’s heat and drought.

Fragrant-leaved native shrubs and perennials can spice up your garden: Cleveland sage (Salvia clevelandii) and California sagebrush (Artemisia californica) are the classic perfume of Southern California’s chaparral. Hummingbird sage (Salvia spathacea) and fragrant pitcher sage (Lepechinia fragrans) both have sweet fruity fragrances, each unique from the other.

Try some wonderful fragrant-flowered natives: California lilacs (Ceanothus sp) have subtly sweet flowers, while the orange blossom fragrance of mock orange (Philadelphus lewisii) can fill your entire garden. If you like the smell of grape bubblegum, plant woolly blue curls (Trichostema lanatum).

Every garden needs drought-tolerant trees — as many as possible. Strawberry tree Arbutus ‘Marina’ has gorgeous shreddy mahogany colored bark with bright green leaves and pink flowers in spring. Gold medallion tree (Cassia leptophylla) is a narrow, medium-size tree with bright yellow flowers that turn into long, festive green bean pods. Tecate cypress (Hesperocyparis forbesii) is a Southern California native that is rare in habitat but readily available in nurseries. It is a far, far better choice than Italian cypress.

For spring flowers, plant seeds of California native poppy (Eschscholzia californica), elegant Clarkia (Clarkia unguiculata), baby blue eyes (Nemophila menziesii), California goldfields (Lasthenia californica), and Common tidy tips (Layia platyglossa)

Plant flowering sweet peas seeds now for bloom in spring. Renee’s Garden Seed,, specializes in these fragrant beauties. Check their website for a wide selection of seeds.

Succulent aloes put on a beautiful show this time of year. One of my favorites is Aloe rubraviolaceae, a low-growing rosette type Aloe whose teal leaves are edged in soft rose. Each rosette features a single, tall candelabrum of stout, poker-style flowers that bloom red orange.

Mangave are all the rage right now. These easy-growing Agave/Manfreda crosses form small- to medium-size succulent rosettes. The blades are most green or blue-green, some with yellow stripes. Each variety features a different pattern of burgundy or brown spots and an imaginative name like ‘Mission to Mars,’ ‘Bad Hair Day,’ ‘Cherry Chocolate Chip,’ ‘Bloodspot’ and others. Grow them in the ground or in pots, in well-draining soil and full sun.

Visit your favorite nursery to reserve bareroot fruit trees and shrubs that arrive next month: blueberries, peaches, apples, nectarines, pears, apricots and more.

Edible gardens

Before you replant pots or raised beds, add compost to bring the soil level back to the top. Sprinkle in earthworm castings and vegetable fertilizer. No need to dig it in — that happens naturally.

Plant winter root vegetable seeds (not seedlings) now: beets, turnips, radishes, carrots, rutabagas, parsnips.

Plant greens and cabbage family plants from seed or seedling: kohlrabi, kale, spinach, Brussels sprouts, cabbage, rapini, broccoli and more.

Plant annual parsley, dill and cilantro from seed. These annual herbs do best in vegetable gardens.

Plant perennial oregano, thyme, marjoram, sage and rosemary from 4-inch or 1-gallon pots into a permanent spot in the garden. Since they are all waterwise Mediterranean natives, plant them in ornamental garden beds.

To harvest greens — including lettuce, kale, spinach, bok choy and tatsoi — simply cut off as much as you need and let the plants continue to grow. Harvest herbs the same way.


How thick is your garden’s mulch? Aim for a minimum of 3 inches over every garden bed. Be sure that irrigation lines are under the mulch, not on top.

Mulch succulents with rock or gravel. Mulch nonsucculents with aged woody mulch or with fresh wood chips that are smaller than an inch. Larger fresh woodchips can bringing deadly borers into your garden. Aged wood chips are not problematic.

Sterman is a waterwise garden designer and writer and the host of “A Growing Passion” on KPBS television. More information is at and

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