Irrigation is the artificial application of water to soil in the correct amounts and frequency for optimal soil infiltration and plant growth.
Why is irrigation “artificial”? Think of turf grass. Many of us have it in our front and back yards with in ground irrigation. In some parts of the world, such as the United Kingdom or New Zealand, turf grass grows without any irrigation. Even in parts of the United States, turf grass grows without irrigation, except perhaps dragging a sprinkler attached to a hose across the lawn in the peak of the summer. But in Southern California, turf grass needs irrigation for much of the year to maintain plant health. Irrigation is “artificial” application of water because you are providing the water rather than relying on rainfall.
What is the “correct amount” to irrigate? Santa Clarita Valley soil is predominately clay, which does not allow optimal water absorption and tends to create runoff. In order to reduce surface runoff, watering times should be broken into multiple cycles with shorter irrigating periods. To avoid losing water to evaporation, watering times should be between 2 a.m. and 6 a.m. Many people find success with watering times of three minutes with spray irrigation, which is long enough to allow for absorption, but short enough to prevent run off.
What is the “correct frequency” for irrigation? Many people find three watering days in summer and two in winter work well. In the fall, as the hours of daylight decrease and the temperatures cool, you can easily shift to two days a week for turf grass. We hear from many people that they turn their irrigation systems off entirely later in the winter when it rains.
For more information on landscape, visit our Lawn Replacement web site for tips: https://conservation.clwa.org/program/study_guide/lawn/