In a xeriscape-type landscape, the goal is to minimize the amount of supplemental water applied to the landscape. Therefore, routine irrigation should be needed only in the high-water-use zones. Occasional hand watering or a portable irrigation system, such as porous pipe, can be used as needed in the moderate-water-use zones. Established plants in low-water-use zones would receive only natural rainfall and no supplemental irrigation water except in extreme drought.

Operate Sprinklers at Night

When you irrigate affects water-use efficiency. The best time to irrigate with sprinklers is after 9 p.m. and before 9 a.m. During this time there is generally less wind, a lower temperature, and less sunlight, resulting in less water loss to evaporation. Dew formed during the night does not increase disease problems. Drip irrigation systems can be operated at any time of day because the foliage stays dry and therefore evaporative water loss is not a problem.

Use an Automatic Controller to Help Save Water

An automatic controller attached to the irrigation system turns the system on and off and controls the water flow through the various zones according to a pre-set time clock, as shown in Figure 3. It allows you to set the length of time each zone operates as well as the days of the week and time of day the system operates. An automatic controller, however, does not re- lieve you of the need to monitor the system's operation closely. The controller should be reprogrammed frequently during the growing season because water needs change from week to week.

A rainfall sensor attached to the controller detects rainfall and prevents the irrigation system from operating if significant rainfall has occurred. Another type of sensor measures soil moisture and overrides the system when soil moisture is adequate. Sensors are especially useful if the system cannot be monitored and adjusted regularly.

You can buy many different types of controllers. Make sure you get one with the features you need. When managed properly, an automatic controller can pay for itself in reduced water usage, cost, and labor.