Grass clippings are a good source of nutrients for your lawn

Last Updated: 
April 30, 2008

CORVALLIS, Ore. – You can cut your fertilizer use by leaving those clippings on your lawn.

Research in the Oregon State University Department of Horticulture has shown that the fertilizer application rate can be cut almost in half when clippings are returned to the lawn with a mulching type rotary mower.

"And on climax bent grass lawns growing in clay soils, we have produced acceptable quality turf for as long as 12 years without adding any fertilizer at all," said Tom Cook, OSU Extension turf grass specialist.

"People who use grass clippings to mulch shrubs and flowers are simply 'robbing Peter to pay Paul,'" said Cook.

Mow your lawn frequently if you plan to leave the clippings, Cook advises. Your grass should be cut often enough so that not more than one-third of the grass blade is removed at any one time. That means mowing about once a week during the growing season, he said.

Light, frequent mowing will not leave piles of heavy, wet clippings on the lawn. If the lawn is too high, you will need to rake clippings or the grass underneath may be smothered.

Be sure to set the mower at the optimum height. Mowing grass too short can reduce its density and increase the invasion of other grasses and weeds.

On the other hand, several problems may develop when grasses are cut above their optimum height, explained Cook. For example, Kentucky bluegrass is more susceptible to stripe rust and perennial ryegrass tends to shred if mowed above two inches. Colonial bentgrass will develop high crowns, and looked scalped and brown when mowed at two inches or higher.

Despite rumors to the contrary, clippings do not promote thatch build up. Clippings break down quickly, often in a matter of a few weeks. However, thatch may increase as mowing height increases.

For more information about mowing turf grasses, refer to Cook's OSU Extension publication, "Maintaining a Healthy Lawn in Western Oregon" EC 1521.

Or call 1-800-561-6719 to order a printed copy.

Author: Carol Savonen
Source: Tom Cook