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Is it time to water the lawn?

Media contact:

Robert E. Thomas
Information Specialist
University of Missouri Cooperative Media Group
Phone: 573-882-2480
E-Mail: thomasr@missouri.edu

Published: Monday, June 22, 2009

Story source:

Brad S. Fresenburg, 573-442-4893

COLUMBIA, Mo. – Most Missouri lawns have had plenty of water during this year’s cool, wet spring, so homeowners may not be thinking of how to properly irrigate those lush, green lawns now that the year’s first summer heat blast has arrived.

Signs that a lawn needs watering include purple-blue wilting leaves, footprints that persist for several hours and folded or rolled leaves, said Brad Fresenburg, University of Missouri Extension turf researcher.

“Water only when the lawns tell you to. Become familiar with these symptoms and water within a day of spotting them,” he said.

Lawns in Missouri may need one to 1 1/2 inches of water a week from either rain or irrigation to stay green and growing. Grasses not watered adequately will show symptoms of wilt and later turn completely brown. Browning means the aboveground portion of the grass is dormant while the lower portion remains alive but not growing.

Summer dormancy helps grasses survive, but there’s no guarantee that a browned-out lawn will fully recover, Fresenburg said. Dormant lawns should receive at least one inch of water every two or three weeks to prevent complete turf loss. Thorough watering will bring the lawn out of dormancy, allowing growth to continue.

Do not water a lawn if the soil is moist, even if grass shows signs of wilt. Lawns with shallow root systems in saturated soil are susceptible to “wet wilt,” which causes root damage due to oxygen depletion.

Water a lawn between 6 a.m. and 8 a.m., when water pressure is highest, wind is low and water loss to evaporation is negligible. Lawns watered in the evening remain wet throughout the night, which can encourage the development of turf diseases.

Move sprinklers frequently enough to avoid creating puddles and runoff. Hand-water areas that wilt before other parts of the lawn. These hot spots may be due to hard soils that take up water slowly.

To avoid under- or overwatering, determine the delivery rate of your sprinkler system. You can do this by placing rain gauges or cans where the sprinkler is running and measuring the depth of water after an hour. Most soils in Missouri will take in only about half an inch of water per hour. If your sprinkler’s delivery rate is more than that, you will need to adjust your irrigation schedule accordingly.

For more information, see MU Extension publication G6720, “Home Lawn Watering Guide,” available for purchase or free download at http://extension.missouri.edu/publications/DisplayPub.aspx?P=G6720.

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