CINCINNATI, Ohio - Turfgrasses throughout many parts of Ohio, especially in the north and northeast, are turning brown to counteract the stresses associated with lack of sufficient rainfall and hot weather.
Joe Boggs, an Ohio State University Extension Southwest District horticulture specialist, said it's not unusual for cool season turfgrasses, like fescues, perennial ryegrass, and Kentucky bluegrass, to enter dormancy to preserve water and nutrients, but stressed the importance of keeping them healthy during drought situations.
"Turfgrass is genetically engineered to shut down if it gets too hot or too dry. It enters a stage where no blades are being produced, the root system stops growing," said Boggs. "The only thing that is alive is the crown, which sits right on the soil. If the crown dies, the grass dies." Healthy turfgrass can tolerate up to four or five weeks of dormancy before the root system begins to fail and the crown dies, but many other stress-causing conditions may speed up the process requiring homeowners and lawn care professionals to intervene and provide additional maintenance. Boggs said that such factors as poor soil fertility, poor mowing, heavy thatch and heavy traffic affect the condition of dormant turfgrass.
"Understand what you have - what kind of soil you have and what variety of turfgrass you have," said Boggs. Clay soils, for example, harden under dry conditions, leading to root desiccation and water runoff. Kentucky bluegrass creates a thatch, or non-decayed stem material, between the crown and the soil that repels water if it gets too thick. "The thatch layer should be no more than an inch thick," said Boggs. "A homeowner can punch holes in the thatch layer using hollow-core aeration to help break down the thatch layer more quickly." Homeowners should also mow high and in the early evening when it's not so hot. "Keeping the blades cut real short sends carbohydrates, or food for the plant, to the top of the blades, rather than the root system," said Boggs. Blade heights should be between two and half to three inches. Homeowners can also return grass clippings to the lawn for added water and nutrients. Clippings contain 75-80 percent water.
Boggs added that in situations when dormant turfgrass does need to be watered, homeowners should do so early in the morning. "There's not much evaporation going on in the morning," he said. "A half inch of water per week is enough to keep the crowns alive without breaking dormancy." Traffic should be kept to a minimum on dormant grass, as the soil compaction stresses the grass and damages the crowns. Boggs also recommends that homeowners don't fertilize dormant turfgrass, as the fertilizer will not be absorbed and may actually damage the grass.
Above all else, Boggs urges homeowners not to assume that all brown turfgrass is dormant. "Disease, and insects, such as billbugs and chinch bugs can cause grass to turn brown," he said. "If you see the rest of your neighborhood's lawns are brown, then there is a good chance it's because the grass is dormant. But if only patches of your lawn are brown, then an insect problem could be the cause."