As the severe drought persists across much of the Intermountain West, gardeners here are facing another dry growing season.
Last year, some communities in Arizona, Colorado, and New Mexico asked residents to voluntarily reduce water use, while others issued mandatory restrictions on outdoor watering.
Now, as summer approaches, many reservoirs are still less than half full. To conserve scarce supplies, water managers will probably have to implement restrictions again.
In severely impacted communities, one of two scenarios is likely to prevail. In the less drastic scenario, lawn watering would be restricted to two days a week, if water supplies allow. In the worst case, lawn watering would be banned and only trees and shrubs could be watered. In any case, there are water-saving practices you can adopt to maintain your existing plants.
1. Assess your priorities. Survey your landscape: What areas or individual plants do you want most to save? There's no point in wasting water by trying to keep alive scraggly or diseased plants. No matter what else you have to sacrifice, give top priority to irrigating established trees and shrubs; they're virtually irreplaceable. Consider perennials a second priority.
2. Identify root zones. The roots of various plants grow to different depths; the trick is to apply just enough water to moisten the roots without going beyond. Most tree roots are located in the top 2 feet of soil. The drip line of a tree or shrub runs around the perimeter of the canopy and virtually outlines the root zone on the ground below. Once you identify the root zone, focus your resources on that area.
3. Check soil moisture. To determine how dry or moist the soil is below the surface, dig down at least 12 inches with a trowel or spade and take a handful of soil and squeeze it; still-moist soil will hold together in a tight ball. An even better way to investigate is to invest in a sampling tube to "read" your soil. When you push the metal tube into the ground and twist it back out, it extracts a 12-inch or longer core showing in cross section how wet or dry the soil actually is. For example, if your soil sample is powder dry on top and barely damp below, it's time to water. Tube samplers ($23 and up, plus shipping) are available from Forestry Suppliers ( www.forestry-suppliers.com or 800/647-5368).
4. Build watering basins. Mound soil berms around young trees and shrubs such as roses to concentrate water on the root zones. Form the main berm just outside the tree's drip line; make a second berm 4 to 6 inches from the trunk to keep water off it.
Don't use your thumb to direct water from a bare hose end. Install a soft spray head or watering wand with an on-off valve. Don't spray water on foliage; apply it directly to the soil or mulch around plants' root zones.
5. Irrigate slowly and deeply. Slow soaking limits runoff and encourages plants to develop deep root systems that are better able to tolerate drought.
To minimize evaporation, irrigate in the early morning or evening, when the air is cool and calm.
6.Modify lawn care. If local restrictions allow lawn irrigation, there are some things you can do to reduce the amount of water you apply. Mow grass higher--2 to 3 inches for bluegrass, 2 1/2 to 3 inches for tall fescue--to help shade the roots below. Don't overfertilize; too much nitrogen only encourages thirsty new growth. Some gardeners cut back to 1 inch of water every two weeks; under this regime, lawns turn straw-colored and semidormant but bounce back after the weather cools in fall.
7. Apply mulch. To conserve soil moisture, spread a 2- to 4-inch layer of organic mulch such as shredded bark, straw, or weed-free hay over the root zones of permanent plants. Mulch trees all the way out to the drip line, but keep the mulch 6 inches from the trunk to prevent rot. Mulch also blocks weeds, which steal water and nutrients needed by desirable plants.