The Pros and Cons of Mulching Your Fall Leaves

2. Reduces Waste and Saves Time

Instead of raking, bagging leaves, and disposing of them—a chore that requires time and effort—mulching allows you to repurpose them right on your lawn. By mulching, you reduce the need for bags and lower the volume of yard waste sent to landfills, and you'll have your weekend back.

3. Supports Local Wildlife and Soil Microorganisms

A mulched layer of leaf bits can provide food and shelter for beneficial insects, worms, and soil microorganisms. Don't confuse this with leaving a full layer of heavy leaves on the grass—dime-sized pieces of leaves are more likely to become supportive organic material and a natural fertilizer. Additionally, leaving a thin layer of mulched leaves in garden beds can protect overwintering pollinators and other small creatures, which contributes to biodiversity in your yard.

4. Suppresses Weeds Naturally

Mulched leaves create a layer that helps smother common lawn weed seeds, reducing their ability to germinate in spring. By blocking sunlight, this leaf layer acts as a natural weed barrier, saving you from using chemical weed killers and reducing time spent weeding your garden.

Potential Downsides of Mulching Leaves

1. Risk of Lawn Damage if Overdone

Mulching too many leaves at once or leaving large, unshredded leaves on the lawn can suffocate the grass beneath. Just like if you were to leave a big mound of grass clippings on your lawn, thick piles of shredded leaves can also lead to patches of dead grass and increase the risk of fungal diseases, especially in damp or shaded areas. A thin layer of finely shredded leaves is usually safe, so if you have a heavy leaf fall, consider a mix of mulching and raking to collect extra leaves.

We live in a heavily wooded lot, and in areas where grass growth is already compromised, we find it safest to collect the leaves in our Cyclone Rake and relocate them to the compost. In parts of the yard where the grass is healthy, we mulch fallen leaves all season.

2. Potential for Clogged Mowers and Extra Work

For those with smaller or less powerful lawnmowers, mulching isn't always easy. Thick piles of leaves can clog up a regular lawn mower, especially if they’re wet. Using a mower with a mulching blade or a leaf shredder attachment can make the process easier, but if your equipment struggles, mulching may not feel like the efficient method you expect.

3. Mulch May Not Be Suitable for All Flower Gardens

While mulched leaves generally benefit lawn grass, they can sometimes create issues in garden beds. For example, a thick mulch layer could retain too much moisture and prevent air circulation around perennials. It may also cause root rot in moisture-sensitive plants. Additionally, some leaves (like black walnut leaves) contain chemicals that can hinder growth in certain plants, so it’s essential to know what types of leaves you’re mulching and where you’re applying them.

Tips for Effective Leaf Mulching

Here’s how to make the most of mulching leaves in your yard:

• Shred Leaves Thoroughly: Use a mower with a mulching blade or leaf shredder to chop leaves finely. Mowing leaves helps them decompose faster and prevents clumping.
• Mulch Only When Leaves Are Dry: Dry leaves shred more easily and are less likely to clog your mower. Wet leaves can cause clogs.
• Don’t Over-Mulch: Aim for a thin, even layer on your lawn. If you have more leaves than you can reasonably mulch, consider adding some to your compost piles, or using them like store-bought mulch around the base of trees or in your garden.
• Use Different Leaves Wisely: Some leaves, like maple and oak, make excellent mulch; however, avoid mulching leaves from toxic or allelopathic plants (like black walnut and black cherry tree leaves) near sensitive plants.

Can mulched leaves harm my lawn if left over winter?

In most cases, mulched leaves won't damage an otherwise healthy lawn if they’re finely shredded; however, large, thick piles of leaves that remain unshredded can block sunlight and trap moisture, which may damage the grass underneath and lead to mold growth.

Is mulching leaves better than composting them?

Both offer great benefits, but they serve slightly different purposes. Mulching leaves directly on your lawn immediately improves the soil health, while composting them in a pile allows them to break down more completely. Composting also makes it easier to store leaf material for later use.