Use drip irrigation on trees and shrubs in the water-use zones of the landscape. Locate the emitters within the drip zone line of plants where the concentration of absorbing roots is the highest. During extended dry periods, operate the system one or two times per week. Run the system long enough to thoroughly wet the soil six to eight inches deep. Regular and thorough watering of newly planted trees and shrubs encourages good root establishment and greater drought resistance.
Herbaceous ornamentals vary widely in their tolerance to drought.
Some perform adequately with a minimum of supplemental water, whereas others require close attention to soil moisture. Irrigation can be provided most efficiently if the plants within a bed have similar water needs. Herbaceous ornamentals generally have a shallower root system than woody ornamentals and are among the first plants in the landscape to show water stress during dry periods. Water these plants once or twice a week and use drip irrigation whenever possible. Be sure to mulch the entire bed area with three to four inches of organic material.