Home & Garden

Let fallen leaves lie? Not without chopping them

A home with leaves covering the front lawn, right, next to a home where most of the leaves have been raked to the curb in Akron, Ohio.
A home with leaves covering the front lawn, right, next to a home where most of the leaves have been raked to the curb in Akron, Ohio. TNS

Maybe you saw the National Wildlife Federation’s recent advice to let your fallen leaves lie.

Woo hoo! you’re probably thinking. No more raking!

Whoa, there, Lawn Ranger. Not so fast.

An article by the federation that recommends leaving fallen leaves in place has gone viral on social media. If you read the whole story, you know it included one key bit of advice: Use a mulching mower to chop leaves that fall on the lawn.

Trouble is, some people read just the headline or maybe the first few paragraphs, and they missed that vital information.

If you let whole leaves lie on your lawn, they can form a decaying mat over winter that kills the grass beneath, said David Gardner, a turfgrass management specialist at Ohio State University. Some of the leaves can also blow into storm sewers and clog them, he said.

Leaves left on the lawn need to be chopped first, which may take multiple passes with a mulching mower, Gardner said. You can use a regular mower if you don’t have one that mulches, but it may leave the debris piled in rows that will need to be distributed over the grass with a rake.

The small pieces will break down much faster than whole leaves and filter down into the soil, where they’ll decompose.

As long as you can see grass among the leaf bits, you should be fine leaving the chopped leaves in place, Gardner said. If the layer is thicker than that, you’ll need to rake off the excess. You can compost those extra leaf bits or use them as garden mulch.

Chopped leaves have long been touted as beneficial for turf because they add organic matter to the soil, but Gardner said newer research indicates that the benefit may not be all that significant. Leaves are about 95 percent water, he said, so there’s not much dry matter left to add to the soil.

On the other hand, Gardner said the research shows there’s no harmful effect from leaving chopped leaves on grass, either. And besides saving your back, there’s another big benefit: It keeps leaves out of landfills. Leaves and other yard waste account for 13.5 percent of the stuff Americans throw away every year, according to the U.S. Environmental Protection Agency.

So what about the leaves that fall on other parts of your yard?

As long as they’re not on grass, they can be left in place to provide food, shelter and nesting material for wildlife, the National Wildlife Federation pointed out in its article. You can just leave them as is, or you can combine them with sticks to make brush piles.