Will Leaves Left on the Lawn Over the Winter Kill the Grass?

The more modern, mechanized and clean the American home is, the greater the temptation to get rid of every shred of natural debris--whether it be bits of bark, grass clippings or leaves. And after all, you didn't buy that big leaf-bag mower attachment for nothing, right? Actually, leaving your leaves will not hurt the lawn, if you know what to do. Moreover, some landfills now refuse to take leaves. They are taking up too much space.

Leaves will hurt your lawn of you leave them in big piles. A pile of leaves is too dense to allow light and air in. Any lawn needs sunlight, and air circulation helps leaves to compost down, so when you finally clean up the leaves in the spring, you are likely to find a big bare or yellow spot where the leaves were and the leaves themselves will be a slippery mess.

If you evenly spread the leaves around the lawn, they will not harm your grass. According to Purdue University researchers Zac Reicher and Glenn Hardebeck, mulching leaves into the grass will not hurt it. Also, they say, in and of themselves, leaves do not add a lot of nutrients, and neither do they control weeds or disease. Worms, however, eat leaves and worms both aerate and fertilize lawns.

It is best to shred the leaves, which you can do by pushing a rotary mower, preferably one with a built-in mulch grinder, through them after you spread them out. You can use a leaf rake to spread them about. As long as the top 1/2 inch of grass receives light, your lawn should be fine, but you will find after shredding them that they mostly sink between the blades of grass anyway.

In large quantities, oak leaves may be too acidic for a lawn.

Leaves that you have mulched into the grass will not create lawn thatch; nevertheless, give your lawn a good raking in the spring. Use a garden rake, not a leaf rake. A garden rake will both help to aerate the lawn and work in the last of the shredded leaves, if any is left at all.