Leaves make great winter mulch for trees and plants
In the woods, leaves cover the soil. They form a rich layer of decaying plant matter that insulates the roots of trees and other plants and provides them with nutrients as it decays.
That’s the way it works in nature. Yet in our yards and neighborhoods, where trees give us so much beauty and shade, we busily rake those life-giving leaves away every autumn. What gives?
“Most people rake leaves because they assume that’s what you’re supposed to do, or because they think leaves are untidy,” said Sharon Yiesla, plant knowledge specialist in the Plant Clinic at the Morton Arboretum in Lisle. “They don’t realize how valuable the leaves are to plants or how useful they can be in the garden.” In some suburbs, homeowners even pay to have leaves hauled away.
Instead of clearing all the leaves away, save yourself work and money and let at least some of them lie. “Rake leaves off the lawn,” Yiesla said, “but there’s no need to remove them under trees and shrubs or in perennial beds. They’ll make a great winter mulch.”
By spring, most of the fallen leaves will have been broken down by fungi, insects and other beneficial organisms. “That improves your soil,” Yiesla said. “It’s free fertilizer, and it will help your soil drain better.” Soil that is enriched by the slow decay of leaves over time becomes lighter in texture and easier for roots to penetrate.
The leaves you rake off the lawn have many uses in the garden. Here are just a few, according to Yiesla:
Insulation. For tender plants such as hybrid tea roses, make a chicken-wire cylinder and fill it with dry leaves to protect the plant from drying in winter wind and cold.
Compost. Add leaves to your compost pile. “In a good compost pile, autumn leaves are an important component,” Yiesla said. “That brown material is carbon-rich, and it creates the structure of the compost.” Mix in some nitrogen-rich material such as green leaves and stalks from dead annuals and fruit and vegetable scraps.
Mulch. You can use whole leaves as a healthy layer over garden soil, or shred them into smaller pieces by going over a pile in the grass with the lawnmower. “Shredded leaves will break down faster,” Yiesla said, and they won’t blow around as much when spread on perennial beds. In less conspicuous corners, there’s no need to shred the leaves.
Vegetable mulch. Stash away leaves to use for mulch next spring in your vegetable garden.
Leaf mold. A heap of leaves left alone will partially break down in a year or two to make a dark, rich, handsome material called leaf mold. That’s what the arboretum uses to mulch all its ornamental beds and as a soil amendment.
“Leaves are free,” Yiesla said, “but they’re worth too much to just throw them away.”
For tree and plant advice, contact the Arboretum’s Plant Clinic (630-719-2424 or plantclinic@morton arb.org). Beth Botts is a staff writer at the Morton Arboretum in Lisle (www.mortonarb.org).