The Impact of Leaves on Grass

Benefits

• Shredded leaves make an excellent top dressing for lawns. They decompose throughout the winter, returning nutrients to the soil and encouraging a healthy microbial balance. In spring, the enriched soil gives your lawn an extra burst of growth. Not only are shredded leaves environmentally healthy for your lawn, but mulching leaves in your backyard keeps them out of crowded landfills; in many areas, fallen leaves and other yard debris make up to 20 percent of residential landfill waste.

Drawbacks

• With leaves, a little goes a long way. Too many leaves on your lawn will smother the grass, prevent sunlight from reaching the blades and creating cool, wet conditions perfect for snow mold, a grass-killing fungal disease. Make sure the grass blades are visible through the shredded leaves, and rake any excess. If the local trees have suffered from fireblight or other transferable diseases, rake and dispose of the infected leaves to prevent the overwintering spores from reinfecting your trees next spring.

Methods

• If you have a lawnmower, your fall chores are simple: Mow the leaves where they fall. Make enough passes to clip the leaves into small pieces that filter easily into the grass. Because many turf grasses keep growing through cool fall temperatures, rake excess leaves and incorporate them into flowerbeds or compost piles. Watch out for certain tree species, such as sycamore or oak; they have thick, leathery leaves that resist shredding and easily smother grass. Rake such leaves from the lawn as soon as possible.

Considerations

• Leaves in compost piles are dry and, despite their original color, do not count as a green, high-nitrogen ingredient, but rather as a brown, carbon-rich addition, similar to straw or sawdust. Add grass clippings or other green, moisture-heavy ingredients to keep your compost bin balanced. Also, a large addition of dry, crispy leaves removes nitrogen from the soil as it decomposes, so add aged compost, manure or a nitrogen fertilizer to your leaf-incorporating lawns or gardens.