Desert gardening

Flower & Garden Magazine, August-Sept, 1996 by Rick Cook

What's Gardening Like In The low desert?

"Different" is the first word that comes to mind-followed by "frustrating" and "rewarding" in about equal measure. Almost everything about gardening in the low desert is different, from the soil to the sunlight to the planting dates to what you plant. Some differences are good; some aren't.

Elsewhere a rubber tree is an indoor plant; the one outside my window is house-high and trying to take over my front walk. Bougainvillea, hibiscus and jacaranda all decorate front yards on my block. I have several thriving pepper plants that are approaching the five-year mark; I harvest my first peppers in March, about the time I set out my last tomato plants. My grape vines and peach trees set fruit in mid-April. If I'm lucky I may harvest my own bananas in a couple of years.

On the other hand, seed catalogs are terminally disappointing. I've learned to skip from the colorful pictures to the U.S.D.A. hardiness zones and check those first. Then I scan the copy for clues as to why a wonderful new find won't grow here. Many beautiful and useful plants -- among them cherries, blueberries, tulips, daffodils and peonies -- simply cannot take the heat and dryness. Even many of the subtropicals that enliven gardens in other Zone 9 areas often won't survive here.

When it comes to plants I have learned never to say "never." Someone somewhere always manages to grow the most unlikely things in the desert. Even acid-loving, cool-temperature plants have been successfully nurtured by gardeners of my acquaintance. While I admire their fortitude, I think they're working way too hard. It is easier and more satisfactory to admit we're different and go from there.

Most of our notions about gardening arose in England or the eastern United States. The farther you move away from those conditions, the more you have to adapt. Scheduling vegetable crops, for example, can be just plain backwards in the desert. Winter is the only time to grow lettuce and other cold-weather crops. So-called warm-weather crops -- tomatoes, eggplant, peppers -- stop setting fruit when the daytime temperature climbs over 100 degrees, as it does for five months out of the year here in Phoenix, Arizona. Peppers, tomatoes and eggplants are set out in February or March in semi-shaded locations and nursed through the summer. Spring and fall are the big fruits hanging on through the summer. Even melons, the ultimate heat lovers, must be handled delicately. If you don't shade the developing fruit it will scald under our blazing summer sun.

One of my first discoveries as a desert gardener was that those U.S.D.A. hardiness zones, based on minimum temperatures, are seriously misleading. For example, those charts suggest that Phoenix shares a Zone 9 climate with central Florida. However, in the desert factors like maximum temperatures and tolerance for low humidity are much more important. Desert gardeners tend to rely on the more elaborate zone system shown in the Sunset Western Garden Book because it reflects those differences more accurately.

A desert gardener quickly becomes familiar with fruit and vegetable varieties adapted to our climate. You learn to plant tomatoes with names like 'Heat Wave' and 'Solar Set,' for example, or 'Anna' apples or 'Thompson Seedless' grapes, because those varieties do well here. Still there are limits. Most stone fruit trees -- except apricots and some plums -- won't live more than a couple of decades in the desert.

Then there's water, which deserts lack by definition. Desert gardening forces you to learn the Tao of watering: infrequently so not to waste it, but deeply to soak the plants, encouraging the roots to go deep and washing salts below the root zone. Drip irrigation systems are quite popular for meeting these needs. Forget that advice about watering in the morning to avoid diseases; serious watering is done at night. With the desert's low humidity, the water doesn't stay on the plants long enough to encourage diseases and daytime watering means more evaporation loss.

Mulch is a desert gardener's best friend. It conserves water, keeps down the soil temperature and helps plants survive our blazing summers. Several inches of everything from grass clippings to hay to pine bark gives your vegetables a fighting chance. As it rots down it also improves the soil, which typically is alkaline and poor in organic matter. If you garden on desert soil, plan to add lots of moisture-retaining organic matter, preferably compost or peat moss. Manure works, too, although it adds more salts to the soil.

For most common plants you need to acidify the soil with pH-lowering additives, such as. and gypsum, which also improve soil texture. Desert gardeners cherish their soil, in many cases building it up over the years from almost nothing.

There's also the matter of caliche (pronounced "cal-EECH-ee"), a sort of natural "concrete" hardpan found in certain alkaline desert soils. Caliche occurs anywhere from the soil surface to several feet down and stops roots cold. The best advice is to remove caliche, which often requires a backhoe. Otherwise, raised beds are in order if it's too close to the surface.