Peter Benjamin, publisher of Nursery News, addressed the subject of water-wise gardening a couple of years ago at an Association of Professional Landscape Designers conference in Albuquerque, where water is scarce.
At the top of his speech he used the term "xeriscape." He explained that many homeowners think the word is "zero-scape" and means designing without plants, and that he has found himself having to pronounce and define the word.
The literal translation of xeriscaping means "landscape design for dry conditions." Through common usage, xeriscape has come to signify ways of getting water to plants more efficiently and keeping it there as long as possible. Therefore, a good way to describe this practice is to call it water-efficient landscape design.
Regardless of the terminology, it's critical to know the cultural requirements that conserve water and keep flora flourishing. Fifty percent or more of residential water consumption goes for plant irrigation, and application of just one inch over 1,000 square feet consumes 600 gallons. So, here are guidelines to help you stretch your water this summer.
* Irrigate according to plant needs rather than by a fixed schedule. Group plants with similar water requirements in beds together. This "zoning" allows plants to be watered as necessary, with minimum waste. For example, an established planting of black-eyed Susans, liatris and purple coneflowers together in a common bed may not require watering all summer, yet moisture-loving ferns, astilbes and impatiens, which prefer cool, protected sites, would wilt and dry within a week without irrigation, especially in a sunny spot.
* Water each area according to its exposure to sun. Each orientation, and degree of shade, must be monitored separately. South-facing slopes dry fastest, so they may require closer attention.
* Put plants with high water needs in low-lying drainage areas or near downspouts. Or try to confine plants that require a lot of water to zones where they are easily accessible to the sprinkler.
* Consider a soaker hose, drip-line or bubbler. One of these systems will release water much more slowly and efficiently than spraying water into the air.
* A sprinkler is the only practical way to water lawns. Many xeriscape designs have greatly reduced amounts of lawn to keep down water consumption. I don't feel that there's a critical need to water turf at the first sign of drought. Turfgrass can make it through three weeks to a month without rain. After that, you should soak it if you don't want to install lawn again in September. Water deeply, one to three times a week. When mowing, leave the grass clippings on the lawn. This helps hold moisture.
* There are groundcovers for full sun that may survive drought better than a lawn will. These include junipers and groundcover roses.
* Compost incorporated into the soil will go a long way toward holding in moisture. Also, aged double-shredded hardwood bark laid as a blanket over a bed will greatly slow the evaporation of moisture from plants' root zones.
You can also raise the water efficiency of your soil with the addition of a state-of-the-art gel, such as Terrasorb or SoilMoist. These water-holding polymers allow the soil to use moisture more efficiently.
Moisture-holding materials, sprinklers, hoses and the other supplies you might need are available at garden and home centers.
To get maximum efficiency from your irrigation, heed the following conventional watering wisdom:
Check soil moisture at varying depths to make sure you've gotten to the base of the plants' roots without watering too deeply. You can stick your finger into the soil and feel for wetness. Or use a screwdriver or quarter-inch-diameter woodendowel to poke into the soil, and check it for moisture.
Water in the morning. Later in the day, much of the water will evaporate; watering at night increases the risk of fungus growth. Don't water during hot, windy or rainy weather.
Repeat watering is especially important on sloped sites and areas where soil percolates quickly. To test your soil for percolation, dig a hole and, before putting in organic material or plants, fill it with water to see how fast it drains. The water should run out slowly. If it drains quickly, you'll need to irrigate the site often.
Use a rain gauge to keep track of how much precipitation your landscape has received. Then you'll have a better idea of when you need to water, without checking the soil.
Avoid using a sprinkler that throws a fine mist into the air. You want droplets to drench the soil. Mist loses too much water to evaporation. Keep ahead of weeds. Weeds use up moisture, and getting rid of them helps keep down the competition for moisture. Move container plants to sheltered areas, away from excess wind and sun.
Lerner is president of Environmental Design in Capitol View Park, Md. His e-mail address is firstname.lastname@example.org.
Regardless of claims that a plant is drought-resistant, the plant still must be watered during the first year or two as it establishes roots in the garden.
Here is a short list of drought-tolerant perennial plants that will get you started: