When autumn leaves fall from the trees, welcome them as though you’d found a treasure chest.
“There are so many ways to use leaves in the garden,” said Spencer Campbell, Plant Clinic manager at The Morton Arboretum in Lisle. “Don’t let them go to waste.”
When you use leaves in the garden, you’re doing what nature does. Soil all over the world is built up continuously by the layer of last year’s leaves and stalks. As that layer of leaves on the ground is gradually consumed by fungi, bacteria, and other organisms in the soil, they release nutrients that plants need and improve the soil structure to make it a better home for plants’ roots.
Leaves are also nature’s insulation. In the woods there is always a layer of leaves on the ground that protects plants’ roots from extremes of hot and cold, holds in moisture and shelters seeds that will sprout and bloom in spring. “When we spread mulch in our yards, we’re just imitating what fallen leaves do in nature,” Campbell said.
Here are some tips from the Plant Clinic for making the most of autumn leaves.
Use leaves for mulch. Simply rake them onto perennial beds or around trees and shrubs, or spread them on vegetable gardens or raised beds. By spring, the leaves will have partly broken down and mostly disappeared as soil organisms consume them and release their nutrients.
Rake most leaves off the lawn. A few leaves won’t hurt, but a mat of leaves left on the turf may encourage disease and will block the sunlight that the grass plants need.
Shred them if you like. Shredded leaves look tidier and won’t blow around as much when they are used as mulch. They also break down faster on the lawn or in a compost pile. To shred leaves, pile them on the lawn and run your lawn mower over them a couple of times. “It’s fine to leave some shredded leaves scattered on the grass," Campbell said. “They’ll break down quickly and improve the soil for your grass.”
Make compost. Leaves are a major ingredient in any successful compost pile. Mix them up with end-of-season annuals, weeds, and selected vegetable and fruit scraps from the kitchen. After a few months, you will have a versatile and powerful soil amendment. Learn more at mortonarb.org/composting.
Insulate. You can extend the fall harvest of some vegetables by using a layer of leaves to protect them against autumn freezes and winter cold. They can insulate late crops, such as cabbage or spinach, when an overnight frost is predicted. If you pile leaves over the beds of root vegetables such as carrots and beets, the soil will freeze more slowly, giving you more time to harvest the roots. Leaves also make good insulation around tender ornamental plants such as hybrid tea roses, contained by a cylinder of wire mesh or by a burlap wrapping.
Save leaves for later. Stash away leaves to use all year long as an ingredient in compost, a way to add organic matter to soil, or mulch over the soil in next year’s beds or vegetable garden. Stow them away in an out-of-the-way corner or in a spare compost bin. Shredded leaves take up much less space than whole leaves.
For tree and plant advice, contact the Plant Clinic at The Morton Arboretum (630-719-2424, mortonarb.org/plant-clinic, or plantclinic@mortonarb.org). Beth Botts is a staff writer at the Arboretum.
