UNIVERSITY PARK, Pa. -- Failure to rake up grass clippings on the lawn is not the sign of a lazy homeowner, but a savvy one. Leaving newly mown grass will not harm your turf--it may even be beneficial, says a turfgrass expert in Penn State's College of Agricultural Sciences.

"If you leave the clippings on the lawn, you can reduce fertilizer needs by as much as one-third," says Peter Landschoot, associate professor of turfgrass science. "When turf is mowed on a regular basis, clippings break down easily, returning nitrogen and other nutrients to the soil.

"It's estimated that 20 percent of what goes into landfills is yard debris such as leaves, hedge prunings and grass clippings," he says. "Recycling grass clippings into the lawn not only is civic-minded, but it also can be beneficial to the lawn and saves the work involved in bagging."

Landschoot shoots down the notion that leaving clippings causes excess accumulation of thatch. "Because the clippings decompose rapidly, they do not contribute to thatch," he says.

For clippings to break down rapidly, the lawn must be mowed frequently enough that large amounts of leaf residue don't remain on the surface of the turf.

"Weekly mowing often isn't frequent enough, especially during the peak period of leaf growth in spring," he says. Excessive accumulations of clippings remain on the surface for long periods and can smother the grass.

More frequent mowing also helps the lawn in other ways. "When you're mowing, you shouldn't take off more than one-third of the leaf blade at one time," Landschoot says. "Otherwise, you may scalp the grass and make it more vulnerable to stress."

If no herbicides have been applied to the grass, homeowners can rake the dried clippings and use them as mulch around trees, shrubs or flowers, says Landschoot.

Lawn mower manufacturers also feature mulching mowers that keep the clippings circulating under the mower deck, chopping the grass blades into finer pieces. "This hastens the decomposition of the clippings and reduces the amount of residue left on the lawn," says Landschoot.

"However, you don't have to buy a mulching mower to recycle clippings. Ordinary lawn mowers also will provide good results."

Grass clippings also can be composted. "If you combine clippings with tree leaves, the two sources of yard waste will complement one another in the composting process," Landschoot says.

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EDITORS: To contact Peter Landschoot, please call (814) 863-2719.

Contacts: John Wall John_Wall@agcs.cas.psu.edu (814) 863-2719 (814) 865-1068 fax