Is It Bad to Leave Leaves on Your Lawn Over Winter?

Short answer: A light scattering of leaves can stay and be mulched into the lawn. A thick layer should not stay over winter. It mats down under snow, blocks light and air, and makes snow mould and dead patches much more likely in spring.

What happens to leaves left on the lawn

Through November the leaves soak up rain. Then the first snow presses them into a wet mat. Under that mat, grass sits in the dark in cold, damp conditions for months. When the snow melts in March, the lawn often shows grey or pink matted patches, thin areas and dead spots that need raking and reseeding.

The light layer test

Look down at the lawn. If you can still see plenty of green between the leaves, mow over them with a mulching mower and leave the shredded pieces. They break down and feed the soil. If the leaves cover the grass, they need to come off.

Other problems with leaving leaves

• Drainage: leaves clog downspout outlets, catch basins and window wells, which slows melt water in spring.
• Slips: wet leaves on walkways and steps are slippery, and they freeze into slick patches.
• Pests: thick piles against the house give shelter to rodents and insects.
• Extra spring work: matted leaves are harder to remove in April than dry leaves in November.

Where leaves can stay

Garden beds and natural areas at the back of the lot can keep a light layer of leaves. It insulates plant crowns and gives shelter to beneficial insects. Keep it loose and away from the house, and remove anything thick and slimy in spring.

What to avoid

• Leaving a full layer on the lawn and hoping snow will hide it.
• Raking only the front yard and forgetting the back lawn.
• Pushing leaves onto a neighbour’s property or into the street.

When to call a professional

If your trees drop more than you can keep up with, book a leaf cleanup for the peak of the drop and a final visit in late November. It is the cheapest way to avoid spring lawn repair.

Questions homeowners ask

Do leaves fertilize the lawn?

Shredded leaves in a thin layer add organic matter. A thick whole-leaf layer does more harm than good.

Will snow mould kill my lawn?

It usually damages the top growth and leaves patches. Raking the affected areas in spring helps the grass recover. Preventing it by clearing leaves in the fall is easier.

Is it fine to leave leaves in the back corner of the yard?

Yes, a loose pile in a natural corner away from the house and lawn is fine.