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Don't waste soil food: Use the leaves that fall

Fallen leaves on the ground.
One way to use leaves is as the major ingredient in compost.
September 27, 2017


When autumn leaves fall, you have a perfect opportunity to enrich your soil for healthier, more beautiful plants. Use the leaves to start a compost pile or just rake them around trees and shrubs to make nature’s mulch.

"In nature, all the plant material that dies in autumn is used by insects and worms and other organisms to enrich the soil," said Meghan Midgley, soil ecologist at The Morton Arboretum. "When you remove it from your garden, you waste all those nutrients."

One way to use leaves is as the major ingredient in compost. Compost is simply "organic matter in some stage of decomposition," Midgley says. It’s full of bacteria, fungi, and other micro-organisms that will live in the soil and help your plants’ roots get nutrients.

Leaves can make up the majority of your compost pile, but by themselves they aren’t a complete meal to support all the biological activity that produces rich, nutrient-packed compost. To support a wide range of composting organisms, mix in some green materials—end-of-season annuals from your pots, the remains of the vegetable garden, or fruit and vegetable scraps from the kitchen.

In a new compost pile, toss in a couple of shovels of garden soil, which will provide all the microorganisms needed to get the process started. Water the pile occasionally to provide the microbes with moisture.

The composting organisms also need oxygen, so your compost will break down faster if you occasionally stir up the pile with a garden fork to let in air.

The pile should be good sized, at least a cubic yard, for efficient decomposition. A large pile will hold in moisture and provide enough insulation to keep some bacterial activity going even during the cold winter.
Leaves will break down faster if you shred them into smaller pieces. Just rake them into a pile on the lawn and run the lawnmower over them.

There’s no need to compost all your leaves. They also make fine mulch. Leaves won't last as long as wood-chip mulch, because they are easier for organisms to break down, but that means they enrich the soil more quickly. While the leaves last, they will hold moisture and insulate the soil from temperature swings.

The lawn is one place you don’t want to let leaves remain over the winter; the grass plants need sun and air. So scoot the leaves around trees or shrubs or onto beds. To keep whole leaves from blowing around, sprinkle a layer of shredded leaves on top.