Leave the leaves: How doing less yard work helps the environment

Mulching leaves into the lawn instead of raking them could produce better grass, suggests new research – and keep giant leaf bags out of landfills. 

Raking leaves, bagging them up, and hauling them away is standard autumnal practice, but scientists and conservationists are beginning to argue you should leave your leaves to be mulched – and risk the side-eye from your tidy-lawned neighbors.

Taking away the leaves does the lawn no favors and simply adds to landfills, claims the National Wildlife Federation.

"Let fallen leaves stay on your property," naturalist David Mizejewski told the National Wildlife Federation. 

Michigan State researchers began studying the effect of leaves on lawncare in the early '90s. They piled leaves onto grass plots to see how much it took to kill a lawn, and they discovered that leaf-covered lawns were among the first to turn green in the spring.

"It's not only not a problem, it's awesome," says Dr. Thomas Nikolai, a specialist in Michigan State University's plant and soil science department, in an interview with The Christian Science Monitor.

Yes, big piles of leaves can inhibit grass growth and even kill the lawn, but mowing the leaf-covered grass breaks leaves into small pieces that enrich the soil and enhance the lawn's "natural fertility," Dr. Nikolai explains.  

"It's almost common sense," he says. "Where the leaves fall, just mulch them in."

Another benefit: A chemical common in maple leaves can discourage dandelions and crabgrass from growing, according to Nikolai's research with Drs. Paul Rieke and Bruce Branham.

Nikolai describes the new lawn care technique as a "win-win-win," because it saves the time and effort of raking, improves the health of the grass, and keeps giant leaf bags out of landfills.

If you really must remove your leaves, says Nikolai, take them no further than the local soccer field.

This suggestion represents a shift from the most common approach to suburban lawn care, which requires conscientious homeowners to rake up all the leaves, creating a tidy lawn and preventing slimy yard build-up under winter rain and snow.

Robert Fulghum described his desire to let fallen leaves lie as downright countercultural in his bestselling 1989 book, "All I Really Need to Know I Learned in Kindergarten."

Mine is the only yard in the neighborhood with leaves, in fact.... I like the way it looks. I like the way it looks very much. My wife does not. The gardening magazine does not like it, either. Leaves should be raked. There are rules....

There is a reason for leaves. There is no reason for mowed grass. So say I.

Mulching solves the aesthetic problem of leaving leaves on the lawn (read: that brown leaf slime that emerges from under the snow in the spring), writes Rebecca Finneran of Michigan State University, because the leaf pieces will sink into the lawn shortly after mowing. That may not satisfy the strictest of yard-keepers, but even some of Mr. Fulghum's "gardening magazines" may relent. 

"The good news is, you don’t have to rake (leaves) entirely," Felder Rushing wrote for HGTV. "A thin layer of chopped leaves spread evenly over the lawn will compost quite readily, 'feeding' your lawn and the earthworms underneath."