For:
By: Daniel E. Mullins
Extension Horticulture Agent
Take Control of Your Irrigation System this Summer
The supplemental irrigation of lawns, perennials and shrubs is one of the most basic landscape gardening practices. Unfortunately, improper watering continues to be a major cause of landscape problems.
The three most important considerations when irrigating are: When is the best time of day to water? How much water should be applied? How often should it be applied?
Early morning is the best time to water an established landscape. The idea is to water early enough that leaves and stems dry off soon after the application. This practice allows as little time as possible for disease organisms to become established, as many require a film of water on the above ground surfaces for 8 hours or more before spores can germinate and infect.
Afternoon or evening irrigation is not recommended because leaves and stems would remain wet all night, providing more opportunity for infection.
Irrigating early in the day is also much more efficient, as opposed to the same application made during mid-day. Once the sun is high and winds pick up, a high percentage of water is lost to evaporation.
Many homeowners estimate the amount of water to apply by choosing some arbitrary period of sprinkling time and have no idea how much is actually being applied. I know this, because I have asked on many occasions. The standard answer is 20 minutes, which means nothing unless the system has been calibrated.
An engineer or a math whiz could apply some formulas using pressure, pipe size and sprinkler head specifications and come up with the exact amount of water that is being applied per minute. There is a more simple way.
Place a half dozen straight sided cans or pans at random throughout the area to be irrigated. Start the sprinkler system, making note of the time. Let it run until you have caught one-half inch of water. This is the recommended amount of water for lawn irrigation on sandy soil. Shrub beds should receive three-fourth of an inch per application.
I have a theory that many people are afraid to take control of their irrigation systems and just let them run at the original setting. Typically the system comes with a control box containing cycle settings, various buttons and other electronics.
Don’t be intimidated. Take control of your system and set the time of application to deliver the right amount of water, and at the time that you want it. Better yet, go to the manual mode and turn water on and off as needed. Check the sprinkler system manual for instructions, or contact the installer. Most reputable irrigation specialists are well trained and can answer questions.
The frequency to irrigate varies with the season, soil and plants that are being grown. In general, think “deeply, but infrequently” when watering. Daily watering of an established landscape is not required or recommended. Irrigation is best done on an as needed basis.
The proper amount of time between irrigations can vary from every 2 days to weekly depending upon the above factors. Remember that a rain of one-half inch or more counts as a watering and irrigation should be delayed for a few days following.
Make
sure that your system has a rain shut off device included. This small piece of equipment can be set to
prevent the system from coming on when a predetermined amount of rain has
fallen. Not only does it save water, but
there is now a state law that requires this device on irrigation systems.