What should you do with your leaves? Don’t send them away. They are a great resource for your garden.

This time of year, leaves are falling off the trees and piling up around your yard. What should you do with your leaves?

Leave them in your garden beds 

A great strategy for garden beds is just to leave the leaves where they fall. They provide numerous benefits.

Leaves provide important shelter for beneficial insects

Bees, butterflies and moths that pollinate your plants, as well as insects such as parasitic wasps that help control pests, depend on leaves in the winter.

Max Ferlauto, a Ph.D. student at the University of Maryland, did research that looked at the impact of autumn yard maintenance on overwintering insects. Ferlauto pursued this research topic because “we are seeing a decline in insect abundance and diversity, especially in urban areas,” he told OSU Master Gardeners.

We know to plant flowers and other native plants that provide nectar for adult pollinators and other beneficial insects, Ferlauto said. And many of us know that the larval stage of pollinators feeds on the leaves of these native plants. We know less about protecting vulnerable dormant stages in the winter, such as the egg or pupa.

As part of his research, Ferlauto retained leaf litter in yard areas where leaves had been removed in prior years. Moth emergence in the spring increased by 83%.

Ferlauto believes that leaf litter helps both insects that overwinter in leaf litter as well as those that overwinter underground. For the latter, leaves may act like a blanket to insulate the ground.

“One of the most valuable things you can do to support pollinators and other invertebrates is to provide them with the winter cover they need.” said Justin Wheeler of the Xerces Society. “The vast majority of butterflies and moths overwinter in the landscape as an egg, caterpillar, chrysalis or adult. In all but the warmest climates, these butterflies use leaf litter for winter cover.” Bumble bees also rely on leaf litter protection, Wheeler added, along with spiders, worms, beetles, mites and more that provide food for birds and other critters.

Other benefits of leaves

• Leaves are really valuable mulch. Leaves are full of nutrients, including nitrogen, phosphorus and potassium, that feed your trees and shrubs.
• They help to suppress weeds that sprout in winter and spring.
• They retain soil moisture.
• They protect the soil and plant roots from extreme cold and heavy rain, reducing soil compaction and runoff.
• Leaves “feed a vast number of microbes in the soil, which are actually the most important crop you can grow, considering that all plant life in your yard depends on healthy soil biology,” said Derek Markham in Treehugger.
• And leaf mulch is free!

A layer of three to five inches of leaves is good. Be sure to leave space around the trunks of trees and shrubs so they get air.

Leave thin layers on lawn or rake into beds 

Your lawn could benefit from a thin layer of leaves. “By mowing over the fallen leaves to turn them into smaller pieces, the leaves will actually enhance the lawn’s fertility, not kill it off,” Dr. Thomas Nikoai of Michigan State University told the Christian Science Monitor.

However, thick layers of leaves could smother the turf, creating thin or bald spots and eventually killing the lawn.

Rake or blow leaves at least once a week during peak leaf fall. Raking more frequently does not take much more time because frequent removal is much easier than waiting to remove all the leaves at once. Dry leaves are easier to rake than wet ones, so aim for a dry day if possible. A good rake makes the job easier.

Many people prefer to rake the leaves off their lawn into garden beds. This is a great strategy (see above). But don’t shred the leaves if you plan to do that. Smaller leaf bits don’t provide as good habitat for beneficial insects as leaves left whole.

Compost them

You could also create leaf piles and let the leaves decompose. Or you could add them to your compost pile, combining them with grass clippings for high-quality compost that provides both carbon and nitrogen to feed your soil. Large leaves will break down more quickly if shredded, but will break down eventually if allowed time.

Do not compost the following, but dispose in yard waste

• Leaves from any tree with a foliar disease, such as fruit trees, ornamental cherries and plums, or dogwoods with anthracnose. Disease spores can over-winter on fallen leaves, surviving the composting process and infecting your trees again in the spring.
• Leaves of conifers and broad-leaf evergreens. They take a long time to compost.

Put them out with your yard waste

You could send leaves off with your municipal yard waste so they can be commercially composted. But do you really want to rake up all your leaves and then give them away, losing all the benefits they provide?

Don’t send them to the landfill

What should you do with your leaves? Don’t send them to sit for years and years in a landfill. In our area, most of us have the option to leaves to be commercially composted. Disposing of leaves is such a waste of a valuable resource!