The unthirsty 100 - plants require less summer water

Sunset, Oct, 1988

Ready for a new water-sensible era in California gardening?

On these 10 pages are your best-bet plants. They're good-looking. They get along with little or no summer watering

Water thrifty or water guzzling? When you set out to save water in the garden, sooner or later you have to reckon with plants' varying thirsts.

The ones on these 10 pages are water thrifty Although their moisture needs vary-depcnding on climate, exposure, and soil, as well as on the plants' basic natures most thrive in home gardens with little or no summer water, once established. They're good-looking and well suited to California's dry summers.

There's good reason to consider planting them now. Low rainfall in the winter of 1987 88 the second year in a row brought serious water shortages to some districts, primarily in northern California. There, mandatory cutbacks ranging from 10 to 35 percent turned lawns brown and stressed other plants.

And fall is the best time to buy and plant drought-tolerant plants. Air is cool but soil is still warm, which promotes root growth. And any rains that fall in the next four to six months will help irrigate them. If you're planting a new garden, you can landscape it entirely with unthirsty plants. If you're renovating an old one, modify it in stages; that way, you'll spread the work and expense over several years and avoid disrupting the whole garden at once.

Mediterranean-climate plants

The list starting on page 77 gives 100 plants for a variety of landscape needs. Most come from Mediterranean climates. Of these, 18 are California natives; the rest are from parts of western and south Australia, southern Africa, central Chile, and the lands around the Mediterranean Sea. A few others just happen to be drought tolerant, even though their places of origin are high-rainfall areas.

In Mediterranean climates, all or most of the year's rain falls during the cooler months, and summers are mostly dry. Many plants native to these areas can survive on very little moisture; their physical make-up allows them to conserve water and use it economically through dry seasons. For example, some are inherently deep rooted and can reach water reserves far down in the ground. Many have hairy or thick leaf surfaces, which help reduce water loss.

Some-many California natives, for instance-go semidormant in summer and can succumb to root rots and other soilborne diseases if watered then.

Getting the plants established

Obviously, plants put straight into the

ground ftom cans won't survive into their first summer without water. To become drought tolerant, they must send roots down to the soil level where some moisture from winter rains remains well into the dry season. You help them to do so, by watering them at planting time and again if rains during the first winter and spring are infrequent or too slight to soak the soil. Water slowly, deeply, and thoroughly two to four times during plants' first dry season (some may need water more frequently). By their second summer, many won't need water.

Other factors determine a plant's drought tolerance: how hot or windy the weather gets during the dry season (the hotter and drier it gets, the more it taxes a plant's ability to survive); what kind of soil it's in (clay holds more water than sand); how deep the soil is (the deeper and more permeable it is, and the more rainwater it absorbs during the rainy season, the more likely a plant is to survive); what the local microclimate is like; how much competition for water there is ftom nearby plants; and whether there's a mulch to help retain soil moisture.

Unthirsty plants alone don't save water How you place them in the garden, and how well you manage the water you give them make the difference between a water-careful landscape and a water-wasteful one. Here are guidelines.

Choose the right plants for your climate. For each plant, use the climate zones in the following listings as a guide. Also consider your site-whether it's subject to drying winds, for example.

Put them in the right place. In nature, plants scatter seed in many directions, but they take hold and thrive only in soils and exposures that especially suit them. In gardens, we sometimes expect them to thrive where we plunk them.

Provide good drainage. If your soil drains well, water percolates downward through and past the rootball. Check your soil's drainage before planting. For corrections that can be made then, see page 210.

Group plants with the same water needs. Don't put ones that can tolerate summer water with ones that can't. And don't put one water guzzler in a bed of less thirsty plants (it'll set the flow for all).

Water wisely. Once plants are established, give them only the water they need to look good-no more. (Many plants initially chosen for drought tolerance subsequently get overwatered.) Water at night or in early morning, when soil is cool (warm, wet soils promote root rot in many susceptible plants, such as those marked with a * in the plant listings).