Drought Management In Your Landscape - July 23, 2003
Jeff Schalau, County Director, Agent, Agriculture & Natural Resources
Arizona Cooperative Extension, Yavapai County
As water for irrigation is becoming increasingly precious, decisions must be made on how to use it wisely. In the southwestern United States, it is not a question if drought will occur, but rather when it will occur, how long will it last, and are you prepared. Just as ranchers and farmers plan for drought, so too must backyard gardeners.
Drought affects different types of plants in various ways. Natives and drought-adapted plants may go dormant for extended periods to survive drought. If moisture stress persists, plant tissue damage can occur, and over time, entire plants or portions thereof may die. Severe moisture stress can also increase susceptibility to harmful insects and diseases.
Some strategies can conserve irrigation water and reduce long-term impacts to home landscapes. The 10 irrigation conservation measures listed below range from moderate to extreme, but consider each one in the context of your landscape.
Arizona, Utah and parts of Nevada remain stuck in the fifth year of a record-setting drought; one that climate watchers say shows no signs of abating. We can all help the situation by conserving water in our landscapes.
- Irrigate highly visible and intensively managed areas first. Drought sensitive plants should have high priority, but turf should have lower priority. Although turf is drought sensitive, it is cheaper to replace turf than to replace trees and shrubs. You may even want to consider reducing/eliminating turf areas permanently.
- Irrigate early in the morning. Less water loss occurs from evaporation and wind drift in the morning because of cooler temperatures and less wind. If possible, don't use overhead sprinklers for trees, shrubs and beds; hand water, flood irrigate, or use trickle irrigation. Greater water loss can occur with overhead irrigation because of evaporation and wind drift.
- Irrigate deeply at long intervals rather than frequent, shallow waterings. Deep watering improves drought resistance by promoting deeper, more extensive root systems. Depth of watering should be 6 to 12 inches for turf and bedding plants, 12 to 18 inches for perennials and shrubs, and 18 to 24 inches for mature trees.
- Placement of irrigation water on trees and shrubs is also critical. A good rule of thumb is to locate the plant's dripline and apply irrigation ½ the canopy diameter inward and ½ the canopy diameter outward (see figure).
- Consider water harvesting: construct swales, collect or direct roof runoff to planted areas, install a properly designed (legal) graywater system (see June 27, 2001 and July 11, 2001 Backyard Gardener Columns on the web site).
- Keep weeds under control; weeds steal water from plants.
- Don't fertilize or, if you do, do so with a low nitrogen fertilizer. Fertilization stimulates growth and increases water needs.
- Add mulch to beds to reduce evaporation from soil and to moderate soil temperature, reducing stress on roots. Final depth of your mulch should be 3 to 4 inches after settling.
- Remove weak plants and/or thin dense beds of plants to reduce competition.
- Under the most severe drought conditions, prioritize importance of plants in your landscape and only irrigate those that provide the greatest benefits. These important plants are often trees that moderate extreme temperatures and/or provide privacy screening. Shrubs may also be important, but consider replacing thirsty species with drought tolerant or native species.
The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at firstname.lastname@example.org and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://ag.arizona.edu/yavapai/anr/hort/byg/.
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