GALENA, Mo. –Hot, dry weather has put lawns to the test this summer. As a result, many homeowners are attempting to keep their lawns active and alive by irrigating.

It’s normal for cool-season grasses such as fescue and bluegrass to go dormant in mid-summer, said Tim Schnakenberg, agronomy specialist, University of Missouri Extension.

“Dormancy is a way for these grasses to protect themselves from difficult conditions,” Schnakenberg said. “Warm-season grasses like bermudagrass or zoysiagrass will continue some growth during the dry summer.”

The good news for cool-season grasses is that their growing season will begin again around September, when cooler nights and more rainfall arrive.

“Unless we have a very severe drought coupled with poor fertility or other difficult growing conditions, most lawns will survive and regenerate in the fall,” he said.

If soils get too dry during dormancy, Schnakenberg says it is a good idea to water occasionally to keep the roots and crowns from drying out.

When watering, remember the best time is 6 a.m. to 8 a.m., when wind disturbance is low, water lost to evaporation is negligible and turf diseases are less of a threat.

Early-morning watering gives the sun the rest of the day to dry off the leaf surface, which means less susceptibility to diseases that thrive in warm, humid environments. Evening watering keeps the moisture on the leaf surface all night.

Move sprinklers frequently to avoid puddles and runoff. Water running off your yard and down the street is a good indication you have watered too long in one area.

“Lawns exposed to drought require only 1.5 inches of water every two weeks to maintain the turf,” Schnakenberg said.

Another smart idea is not to mow the grass too short during the summer. Taller grass has deeper roots and less of a tendency to wilt, so it needs less irrigation. Taller grass also provides shade for the soil surface and lowers the temperature at the base of the plant. Grass ideally should never be less than 2.5 inches after mowing.

“Water only when the grass tells you to,” he said. “Become familiar with areas of the lawn that wilt first. Grass suffering from drought will have bluish-purple leaves, rolled leaves and will keep the impression of a foot after walking on it.”

It is a good idea to irrigate within a day of first observing these symptoms.

Water conservation is important, especially in urban areas. Schnakenberg recommends watering problem areas by hand to postpone the need for irrigating the entire lawn.

“Some areas of the lawn usually wilt before others,” he said. “These hot spots may be caused by hard soils that take water up slowly, changes in soil type or southern exposures.”

For more information on irrigating lawns, see the MU Extension publication “Home Lawn Watering Guide” (G6720), available from MU Extension centers and online at

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