Leaving grass clippings on the lawn

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What grasscycling means

Grasscycling means leaving clippings on the lawn after you mow. Illinois Extension says that if the lawn is mowed as needed and the one-third rule is followed, clippings filter back into the lawn and need not be collected.

Clippings and thatch

Illinois Extension says clippings decompose readily, contain 75 to 80% water, and do not cause thatch. K-State says clippings may contribute to thatch when tall grass is mowed too short and leaves large clippings.

Nutrients

Illinois Extension says clippings recycle nutrients, in particular nitrogen, so less fertilizer is needed. UMN says decomposed clippings add the equivalent of one fertilizer application to a lawn each year.

When to collect

K-State lists four times to collect clippings: when they are long and thick, when they interfere with use of an area, when returning them raises disease risk, or when the equipment requires it.

After herbicides

UMN says that if you have used herbicides on the lawn, leave the clippings on the lawn, and do not use them as mulch on other plants or add them to compost.

Sources: University of Illinois Extension, Mowing Your Lawn; University of Minnesota Extension, Mowing practices for healthy lawns; Kansas State University, Mowing; University of Maryland Extension, Maintaining an Established Lawn.

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