Q. “I’m having a problem with one of the homeowners about watering the lawns. The sprinkler system comes on every morning. The homeowner says we do not have to water our lawns this frequently. To satisfy the homeowner we stopped watering the lawns and they turned brown. Can you help?”
A. The most efficient way to water a lawn is to apply water when the lawn begins to show signs of stress from lack of water. The following signs are indications of water need: dull, bluish-gray areas in the lawn, footprints that remain in the grass long after being made, many leaf blades folded in half and the soil from the root area feels dry. During the winter you may have to rely more on checking for moisture in the rootzone. When the grass shows these signs of drought stress, it should receive about ½ to ¾ inch of water. And don’t water again until the lawn begins to show drought stress symptoms – even in our sandy soils.
How do you know when ½ to ¾ inch of water has been applied? Use empty tuna fish cans or similar containers and place them in the yard within the spray pattern. Turn the water on and time it. If you let the water run for 30 minutes and you find that you’ve collected an average of ¼ inch of water in the cans, then you know you’re applying about ½ inch of water per hour with your irrigation system.
This is important to know because you’re shooting for applying about 1 inch of water once per week even during mid-summer conditions. One-half to ¾ inch of water will move down into the soil about 6 to 8 inches. The roots will grow where there is moisture. If you’re watering too frequently for short periods of time, you’ll develop a shallow rooted lawn that will depend on you watering too frequently. A shallow rooted lawn is more likely to be damaged by summer heat, winter cold, disease problems and root insects.
Lawns will not need to be watered as often during cooler months while the grass is dormant and there is no need to water during rainy weather.
So my answer is to cut the automatic timer to manual and water on an as-need basis. By watering this way, you’ll find that the lawn will gradually require water less frequently because it is developing a deeper root system.