Now that cooler temperatures have arrived (along with shorter days), we're starting to see leaves change color. Over the next few weeks, we can look forward to our landscapes being awash in shades of brown, yellow, orange, and red. As the saying goes, though, all good things must come to an end. Eventually, all of those leaves will end up on the ground, leaving many of us wondering what to do with them.
What to do with tree leaves in the fall?
Mow leaves into lawn
One common concern with fallen leaves is that they will smother and kill turfgrass. This is certainly true if you have a thick layer of leaves on your lawn. However, if only 10-20% of your lawn is covered in leaves, they can be left where they are since they are unlikely to smother turf. However, if the leaf layer is too thick, it can smother and kill the grass.
One option to get rid of leaves on lawns is to mow them. It’s best to mow leaves when they are dry, so they don’t clump together, which can make them more difficult to chop and clog mowers. When mowing leaves, you should be able to see grass beneath the cut-up leaves. Chopping leaves into small pieces allows them to settle between grass blades and reach the soil surface, where soil microbes begin breaking them down. As the leaves are broken down, they will contribute to the organic matter present in soils, and nutrients will be released for turf to utilize.
Add leaves into garden beds
If you have too many leaves to mow, consider incorporating some into your garden beds. Adding a layer of leaves and incorporating (tilling) them into garden soils can help improve them by increasing organic matter. In heavy clay soils, this will help with drainage and aeration, and in sandy soils, it will improve the soil’s ability to hold onto water and nutrients.
If you decide to incorporate leaves into garden beds, it's best to do this in the fall. This will allow plenty of time for the leaves to break down before spring planting. Because leaves have a high carbon-to-nitrogen ratio, they can break down slowly. Applying a small amount of fertilizer after incorporating leaves can help speed the decomposition process.
Use leaves as mulch
Leaves can also be used as a mulch in vegetable gardens, flower beds, and around trees and shrubs.
A layer of mulch can be rather beneficial in our landscapes. It can help:
- Conserve soil moisture
- Moderate soil temperatures
- Prevent soil crusting and erosion
- Control weeds
- Contribute nutrients and organic matter to soils as they break down
When using leaves as a mulch, many people will shred them first to prevent the leaves from clumping together and forming a mat that can prevent moisture from reaching the soil. Many people also find the appearance of shredded leaves to be more attractive than unshredded leaves in a garden setting.
Use leaves to insulate plants
Leaves can be used to help insulate plants too. By using leaves as insulation, we can keep the soil and plants uniformly cold and prevent freezing and thawing cycles that can damage marginally hardy plants (some hybrid tea roses, lavender, figs, etc.). This can be done by placing shredded leaves around the crowns of these plants, or wire frames can be built and filled with leaves. If using leaves as insulation, don’t put them on plants until temperatures are consistently below freezing.
Use leaves in composting
If you’ve ever done any composting, you know how valuable leaves can be as a 'brown' material. For the uninitiated, compost is a dark, crumbly, and earthy-smelling form of organic matter that has gone through a natural decomposition process. If you have a garden, lawn, trees, shrubs, or even planter boxes or houseplants, you have a use for compost. If you’re interested in learning more about compost, check out University of Illinois Extension’s composting website.
While we often dread the appearance of leaves in our yards, they are a valuable and free resource for our landscapes. Before you use up all of your leaves, take some time to make a big pile of them, and relive your childhood.
Leaves can be habitat too
While we’re often in a hurry to clean up leaves in the fall, they can be important overwintering areas for a variety of wildlife. Many insects, including butterflies and native bees, as well as other animals such as salamanders and toads, rely on leaf litter as winter habitat. To conserve these animals, consider leaving part of your landscape, such as garden beds or out-of-the-way areas, as is until spring.
While we often dread the appearance of leaves in our yards, they are a valuable and free resource for our landscapes. Before you use up all of your leaves, take some time to make a big pile of them, and relive your childhood.
Good Growing Tip: Trees pull nutrients from the soil throughout the growing season. Rather than sending fallen leaves away, compost, mulch, or mow them into your landscape to recycle those nutrients back into the soil.
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MEET THE AUTHOR
Ken Johnson is a Horticulture Educator with University of Illinois Extension, serving Calhoun, Cass, Greene, Morgan, and Scott counties since 2013. Ken provides horticulture programming with an emphasis on fruit and vegetable production, pest management, and beneficial insects. Through his programming, he aims to increase backyard food production and foster a greater appreciation of insects.