Hot, dry weather can put a lawn to the test during summer. When that happens, many homeowners attempt to keep their lawns active and alive by irrigating.
It is very normal for cool season grasses like fescue and bluegrass to go dormant mid-summer according to Tim Schnakenberg, agronomy specialist, University of Missouri Extension.
“The dormancy they go through is a way for these grasses to protect themselves from difficult conditions,” said Schnakenberg. “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,” said Schnakenberg.
If soils get too dry even during dormancy, Schnakenberg says it is still a good idea to water occasionally to keep the roots and crowns from drying out.
When watering, remember the best time is from 6 a.m. to 8 a.m. During this time wind disturbance is low, water lost to the atmosphere by evaporation is negligible, and turf diseases are less of a threat.
Early morning watering gives the sun the remainder 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 long.
Sprinklers should frequently be moved 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,” said Schnakenberg.
Do not mow the grass too short during the summer months. Taller grass has deeper roots and less of a tendency to wilt, resulting in less irrigation. Taller grass also provides shade for the soil surface and lowers the temperature at the base of the plant. Grass heights ideally should never be less than 2.5 inches after mowing.
“Water only when the grass tells you to. Become familiar with areas of the lawn that wilt first. Grass suffering from drought will have bluish-purple leaves, rolled leaves and will leave the impression of a foot after walking on it,” said Schnakenberg.
It is a good idea to irrigate within a day after first observing these symptoms.
Water conservation is important, especially in urban areas. Schnakenberg says it is a good idea to hand water problem areas to prolong the need for irrigation of the entire lawn.
“Some areas of the lawn usually wilt before others. These hot spots may be caused by hard soils that take water up slowly, changes in soil type or southern exposures,” said Schnakenberg.
For more information, contact the nearest MU Extension center for a copy of MU Guide G6720, “Home Lawn Watering Guide” or check online at http://extension.missouri.edu.