Leaves on the Lawn: Mulch Them, Don't Rake Them (Mostly)

Every fall millions of homeowners spend weekends raking leaves into bags and dragging them to the curb. On a golf course, we'd never have had the time or the crew to rake every fairway. We mowed them. And for most home lawns, mowing them is the better answer too.

Why mulching works

A mulching mower, or any rotary mower run over the leaves a couple of times, shreds them into pieces about the size of a dime. Those pieces fall down between the grass blades, out of sight, where worms and soil microbes break them down over the winter. You're returning organic matter to the soil instead of hauling it away.

There's real research behind it. In the 1990s, Michigan State University turf researchers mulched oak and maple leaves into Kentucky bluegrass plots for several years and compared them to plots with no leaves. The mulched turf did fine, and the plots that got maple leaves had noticeably fewer dandelions the next spring. It isn't a weed program by itself, but it's a nice bonus for doing less work.

How to do it

1. Mow when the leaves are dry. Wet leaves clump and smother the mower deck.
2. Set the mower at your normal fall height, about 3 inches. Don't drop it low to "grab" leaves; you'll scalp the grass.
3. Make a pass, then look. If you can see grass through the shredded leaves, you're done. If not, make a second pass.
4. Do it often. Mulching a light layer every week or so works much better than waiting until a foot of leaves has piled up.

A mulching blade helps but isn't required. A sharp standard blade with the side-discharge chute closed or a mulching plug installed does a good job too.

When to bag or rake instead

Mulching isn't the answer every time:

• When the layer is too thick. If the leaves are so deep that the grass is buried even after two passes, bag some of them. Run the mower with the bagger on and use the shredded leaves as mulch in garden beds or put them in the compost.
• Under big oaks. Oak leaves are tough and break down slowly. A heavy oak drop may need part of it bagged.
• Wet, matted leaves left all winter. A solid wet mat sitting on the turf through winter blocks light and holds moisture, which is an invitation to snow mold. Don't let a thick layer go into winter on the grass.
• Diseased leaves from trees with leaf diseases are better bagged and removed than mulched back in under that same tree.

Bonus: free mulch and compost

Shredded leaves make one of the best free mulches there is. Spread them 2 to 3 inches deep over perennial beds and around shrubs after the ground starts to cool. In a compost pile, mix shredded leaves with grass clippings or kitchen scraps and you'll have rich compost by spring. Shredding first speeds everything up.

The bottom line

For most lawns, the best leaf tool is the mower you already own. Mow the leaves dry, mow them often, and keep the grass at a healthy height. Save the rake for the beds, the corners and the years the big oak drops everything at once.

Sources (3)

Michigan State University, Leaf mulching research (HortTechnology); Sports Turf Managers Association: Mulched maple and oak leaves associated with a reduction in common dandelion; Colorado State University Extension: Mow, compost and mulch leaves.

Photo: 2022-10-26 08 10 56 Fallen Red Maple leaves on a lawn in autumn along Aquetong L by Famartin, CC BY-SA 4.0.

Related: When to Stop Mowing for the Season (and How Low the Last Cut Should Be)