At first glance, mowing a lawn doesn't look like a difficult job requiring much thought. We're just cutting grass - right?
"But lawn mowing done properly goes several steps farther than just firing up a lawn mower and cutting grass," says Gerald Alexander, Hempstead county extension agent with the University of Arkansas Division of Agriculture.
Mowing is a destructive practice to the plant because it removes a portion of leaf tissue that could be used to provide energy for the plant, he says. When leaf tissue is lost, the plant responds by redirecting energy from storage in the roots to producing more leaf tissue. If a lawn is cut too low, the plant has a more difficult time recovering because it lacks adequate leaf area to help it use soil nutrients efficiently.
Whenever mowing is necessary, never remove more than one-third of the leaf blade in a single mowing. For example, if you want your turfgrass to maintain a height of 3 inches, mow when the turfgrass stands 4.5 inches tall. This will normally translate into a once-weekly mowing pattern under ideal growing conditions, according to Alexander.
Mowing high is preferable to mowing low because overall plant health increases and weed competition decreases. The type of turfgrass in your lawn will determine how high your lawn should be mown.
The suggested mowing heights for common lawngrasses are: Centipede – 1.5 to 2 inches; St. Augustine grass – 2.5 to 4 inches; Zoysia grass – three-quarters of an inch to 2.5 inches; common Bermuda – 1.5 to 2.5 inches.
Alexander says he frequently hears questions concerning grass clippings left on the lawn.
It used to be thought that grass clippings contributed to thatch buildup. However, research has shown that grass clippings don't contribute to thatch buildup. Clippings are actually good for the soil because they return nutrients to the soil when they decompose.
"As long as you don't allow your lawngrass to become excessively high between mowings, you don't need to bag them. Clippings are often bagged because people fear the spread of lawn diseases through the return of lawn clippings. The spores that cause lawn disease are present whether clippings are returned or bagged," says Alexander.
Lawns are best mown when the turf is dry. The clippings are more evenly distributed on a dry lawn than a wet lawn. Wet mowing wet causes the clippings to clump and clog the mower. These clumps will then need to be picked up to prevent smothering the turfgrass beneath. Wet mowing also opens the door for disease organisms to enter the plant. Slipping and tearing turfgrasses are other reasons not to mow under wet conditions.
When lawn mowers are operating, he says, always pay close attention to safety. A mower blade can pick up an object from the ground and throw it with a velocity strong enough to damage cars, houses and inflict serious harm to humans and animals.
Additional information on lawn mowing can be found in the publications section of our web site, or at your county extension service office. The Cooperative Extension Service is part of the U of A Division of Agriculture.
