LISLE, Ill. (Oct. 29, 2024)— The Morton Arboretum is encouraging people to save and repurpose falling leaves to nourish their gardens this autumn. According to the Arboretum’s expert Plant Clinic advisers, leaves make great insulation, compost, and enrichment for garden soil.

“Decomposing leaves enrich the soil by releasing nutrients that support plant growth and strengthen root systems,” said Plant Clinic Manager Spencer Campbell.

Leaves also act as nature’s insulation, protecting plant roots from extreme temperatures and providing shelter for seeds that will sprout in spring. “When we spread mulch in our gardens, we’re mimicking how nature forms a protective, nourishing layer of leaf litter,” Campbell said. The dark brown mulch used throughout the Arboretum’s gardens is made from partially decayed leaves.

Campbell provided these gardening tips for managing and using fallen leaves:

Use leaves for mulch. Rake fallen leaves on perennial beds, vegetable gardens, or around trees and shrubs. By spring, most of the leaves will have broken down and disappeared as busy soil microbes consume them. The leaves can also serve as protective covering for native bumblebees, butterflies, moths, and other pollinators that burrow and hibernate in the soil during winter.

Rake most leaves off the lawn. Lawns only benefit from mulched leaves. Whole leaves can block needed sunlight for the grass.

Consider shredding them. “Shredded leaves look tidier and will not blow around as much when used as mulch,” Campbell said. “They also break down quicker on the lawn or in a compost pile.” To shred leaves, pile them on the lawn and run a lawn mower over them a couple of times. Distribute them more or less evenly, and the small shreds will break down and improve the soil for the 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 kitchen scraps. After a few months, the resulting compost can be applied as a soil amendment, top-dressing, or mulch.

Insulate. Use a layer of leaves in a vegetable garden as insulation against autumn freezes and winter cold to prolong the fall harvest. They can protect late crops, such as cabbage or spinach, when an overnight frost is predicted. When leaves are piled over the beds of root vegetables, such as carrots and beets, the soil will freeze more slowly, allowing 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 burlap, to prevent winter injury.

Save leaves for later. Leaves are useful year-round as an ingredient in compost, as a way to add organic matter to soil, or as mulch in next year’s flower beds or vegetable garden. Stow as many as possible in an out-of-the-way corner or spare compost bin. “Shredded leaves take up much less space than whole leaves, allowing you to stash more away,” Campbell said. “The Arboretum stores leaves behind the scenes in immense piles, where they slowly begin composting while they wait to be used as mulch.”

For more fall gardening tips, visit mortonarb.org. The Morton Arboretum Plant Clinic is generously sponsored by Bartlett Tree Experts.