Everybody loves a freebie: bobblehead doll giveaways at White Sox games, the candy jar on a co-worker’s desk, buy-one-get-one-free shoe sales.
At this time of year, gardeners get a freebie that really is a great deal: the leaves that fall from trees.
“They are nature’s way of enriching the soil and recycling nutrients from one year to the next,” said Julie Janoski, Plant Clinic manager at The Morton Arboretum in Lisle. “They are a great source of organic matter, which improves the soil, they give plants protection from winter weather, and they don’t cost a dime.”
To many homeowners, autumn leaves are just a chore, something untidy to rake up and discard. “That’s a big waste,” she said. “In every bag of leaves you send off for disposal, resources are lost to the plants in your garden.”
In forests and other natural areas the world over, leaves cover the soil. They form a rich layer of decaying plant matter that insulates the roots of trees and other plants. As the leaves decay, they add nutrients to the soil for plants’ roots to absorb.
It’s the model for mulch. “When you apply mulch, you’re basically imitating the layer of leaves that trees naturally create on the ground,” Janoski said. “Homeowners spend a lot of money on mulch, but you can use leaves for free. You even get free delivery.”
Making use of your leaves saves work too. Instead of raking them out of perennial beds and the areas around trees and shrubs, just let them lie. By spring, most of the fallen leaves will have been broken down by fungi, insects and other beneficial organisms. “The nutrients that were stored in the leaves are released into the soil through decay,” she said. “It’s like free fertilizer.”
As leaves gradually break down, they increase the amount of organic matter to the soil and provide food for beneficial organisms. The soil becomes lighter in texture and easier for roots to penetrate.
There’s still some work for a gardener to do. “You should rake leaves off the lawn,” Janoski said. That’s because grass plants, which come from wide-open grasslands, aren’t built to live under a layer of tree leaves. “Just rake them from the lawn onto garden beds,” she said.
Shredded leaves are more likely to stay put in garden beds than whole ones, which tend to blow around. To shred leaves, use a dedicated leaf vacuum or leaf shredder, or gather leaves in piles on the lawn and run over them with the lawn mower. Spread the shredded leaves around the garden, then rake out the last of the pile over the lawn so some shredded leaves can break down to improve the soil of the lawn without smothering the grass.
Here are some other ways to use free and abundant autumn leaves in your garden:
Insulate tender plants. Make a chicken-wire cylinder and fill it with dry leaves to protect a tender tea rose or other marginally hardy plant from winter winds and cold.
Grow vegetables. Dig some leaves into your vegetable beds in the fall to add organic matter to the soil, and save more to use as mulch after spring planting. “Shredding the leaves will make them easier to use around new transplants or sprouts,” Janoski said.
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Make compost. Use dry leaves, which are rich in carbon, as a major component of your compost pile, along with some nitrogen-rich ingredients such as green plants and vegetable scraps. “If you stash away a supply of extra leaves, you can keep adding them to the compost all year,” Janoski said. Shredded leaves break down faster than whole ones. A shredded-leaves stash will also be handy whenever you need a soil amendment or mulch for new plantings.
“If you start thinking of leaves as a resource rather than a nuisance, you’ll find more and more ways to use them,” she said. Some dedicated gardeners even collect leaves from the curbside bags and piles discarded by their neighbors — one person’s trash is a smart gardener’s treasure.
For tree and plant advice, contact the Plant Clinic at The Morton Arboretum (630-719-2424, mortonarb.org/plant-clinic, or [email protected]). Beth Botts is a staff writer at the Arboretum.