5/23/06
Contact: Leslie Johnson
Ron Calhoun
Michigan State University – Michigan Agricultural Experiment Station

EAST LANSING, Mich. -- The best way to deal with grass clippings in your lawn is to return the clippings to the turf. It requires the least extra labor, and it’s good for the lawn, say Michigan State University turf grass specialists. Consistently returning clippings to the lawn can cut your overall fertilizer needs by up to one application a year.

The key to returning clippings to the turf is mowing often enough that you remove no more than one-third of the length of the grass blades at any one mowing, says Ron Calhoun, Extension turf grass specialist in the MSU Department of Crop and Soil Sciences. He suggests raising your mowing height to at least 3 inches. This allows the grass to grow longer between mowings without violating the one third rule. It’s also easier on the grass plants than mowing very short (also known as scalping), which tends to stress the grass plants, especially during hot, dry weather.

Clippings are mostly water, Calhoun notes, and clippings scattered thinly across the lawn dry out and decompose quickly, returning nutrients to the grass plants. Thick layers of clippings are slow to dry out and can smother the turf. Clippings do not contribute to thatch buildup, he emphasizes.

"If the grass gets out of hand and a mowing produces clumps of clippings, you can give them a day to dry and then mow over them again to mince them into smaller pieces and scatter them," Calhoun suggests. Bagging clippings adds extra labor to the mowing job and leaves you with piles of clippings to dispose of. Composting is one alternative, but large quantities of clippings will become smelly unless they’re turned frequently at first -- once or even twice a day.

Composting requires more handling than simply returning clippings to the lawn, and it removes nutrients from the turf. It does, however, produce a handy landscape material that can be used in flower beds, the vegetable garden and landscape plantings.

Using clippings straight from the lawn for mulch has several drawbacks, he points out.  "Thick layers become smelly, and thin layers dry up and blow away," he says. "Thick, wet clippings can mat down and interfere with the movement of air and water into and out of the soil. Be sure to follow the label instructions on the use of herbicide-treated clippings as mulch -- some products can damage landscape or garden plants."