In a grand sense, conserving water in the garden is imperative. Limited supplies, uncertain rainfall and drought are all very real issues on the Central Coast.
It’s easy enough to shift your ornamental plantings to a wide variety of California native and Mediterranean species that require little water or no water. But putting edibles on a water diet can be tricky.
Folks converting to edible landscapes often see their water bills rise after they plant their first crops. The natural inclination is to keep the plants well hydrated, and some edibles — including annual vegetables — need lots of water to sprout, grow and produce delicious food in short order. Sweet summer corn, for instance, is a water hog. I let mine go too dry too frequently last year. The result: stunted stalks and tough, shriveled kernels on the few ears that formed.
However, some veggies, such as garden-fresh tomatoes, actually benefit from reduced irrigation. So while you may use more water to grow your own food, you can also take steps to avoid wasting it.
Good soil prep is essential. Work at least 3 to 4 inches of compost into the top 12 inches of soil. Along with boosting fertility, compost acts like a sponge, retaining moisture and offering nooks and crannies for oxygen to reach the roots of your plants. In clay soil, compost works by pushing apart tiny soil particles to facilitate better air and water movement. In sandy soil, it encourages water to linger, rather than whooshing through.
Run drip irrigation or soaker hose between your plants to apply the water directly to the soil and the roots below. Or hand-water from a bucket or hose. Just don’t splash water everywhere. If you save warm-up water from your shower, store it in a rain barrel so you can water when you need to, rather than arbitrarily emptying a bucket every day. Shape basins around your edibles to prevent runoff, or plant on raised rows with furrows along each side that you can flood. Some water will evaporate, but not as much as if you use sprinklers.
Avoid sprinklers, which can throw water indiscriminately, lose significant moisture to evaporation and hit the leaves and fruit, possibly leading to disease.
Apply an inch or two of mulch to retain surface moisture. Use fine-textured compost, topper, straw or other loose, organic material. Some folks suspend lightweight, translucent row covers over their crops to slow down evaporation. I’ve not tried them, but they might work.
Whatever your method, water in the morning. Your plants will appreciate the moisture as they greet the day. And it’s generally cool and still, so any exposed water won’t evaporate as quickly as when daytime temperatures and breezes pick up.
Do not use an irrigation timer. Most veggies — even those that require regular water — don’t need the next round until the top inch of soil dries out. That moment depends on your mulch, soil type, wind and what’s happening overhead with brilliant sun or overcast skies. A timer is not a substitute for your personal touch.
Check the moisture with a screwdriver or hand weeder. Either one will slide right in if the soil is still damp, or be tough to poke if the soil has dried out. If your plants wilt mid-day, then rebound in the evening, you may not need to water. But if the leaves stay seriously limp, you’re not irrigating enough.
When you do water, soak the soil. As with permanent plantings, you want to promote deep rooting, which comes from saturating the soil, then letting the top inch or so dry out before watering again.
Tomatoes easily top the list. For years, I’ve been promoting teasing out their flavor by limiting the water. Stingy irrigation is simply the best way to concentrate their rich, full taste. Your plants may look terrible, but your harvests will be fabulous. The technique works with tomatillos as well.
As for other summer veggies: once they’ve gained enough size to shade their own roots, peppers and eggplants haven’t been super thirsty in my garden. Potatoes don’t require much water, either. I grew a nice batch of reds this spring without irrigating at all — although a few rain showers undoubtedly helped. This season, I’m planning to limit water to my zucchini plants to see if that can slow down their over-abundant, late-summer production.
In your own garden, there’s bound to be trial and error. You don’t want to water so much that you dilute the flavor. But in withholding water to intensify the taste, you probably don’t want leathery, thick-skinned fruit that yields just a tiny blast of savory goodness.
Yet tinkering with those nuances is what many of us enjoy about gardening. It has a lot to say about how connected to nature we feel when growing edibles. And nothing beats getting it right.
Santa Barbara County has a rich history of this centuries-old technique, which banks winter-time moisture for dry, summer days.
In the late 1800s and early 1900s, local growers dry-farmed wheat, barley, hay, beans, corn, peas, potatoes, garden vegetables and fruit. With the advent of irrigation, first for alfalfa and sugar beets, then for vegetables and other crops, dry farming faded away. But not entirely — Stolpman Vineyards in Ballard Canyon dry-farms its grapes, and last year, I spotted a few acres of dry-farmed tomatoes in Carpinteria.
Dry farming takes prep, space and heavier soil that hangs onto every drop of water. While it’s too late this year, the following is the general idea for vegetable crops.
Grow a cover crop over winter. Next spring, while the soil is damp — but not saturated — till in the cover crop at least a foot deep. Till every few weeks, several more times. The goal is to push the organic material deep into the soil while bringing up residual moisture that’s otherwise locked in below.
A crumby “dust mulch” of dryer soil should begin to form on the surface. Tamp down the dust mulch in late spring to “seal” the soil, then plant your seedlings. Their emerging roots should seek out the subsurface moisture, then follow it downward, developing such a broad, deep network that they won’t need further watering from above.
Your yields may be smaller, but the flavor is often unsurpassed.
This article was first published in the Summer 2013 issue of Edible Santa Barbara.
Copyright, Joan S. Bolton. All rights reserved. Reproduction of text or photos in any form is prohibited without written permission.