Nurturing Nature: Fall Cleanup Strategies

With the growing interest in native and pollinator-friendly plants, home gardeners are learning a new approach to fall cleanup.

Environmental science studies have proven that leaf litter provides overwintering shelter for many insects, spiders, and other arthropods, including caterpillar pupation sites. A University of Maryland study found a 45% reduction in moths and butterflies in leafless garden plots and a 67% reduction in spiders, proving that conventional cleanup strategies are significantly destructive to insects. Fallen leaves also provide insulation for animals overwintering in the ground, such as toads and wood frogs. Decaying leaves enrich the soil, absorb water, and keep moisture available to plants. Flower stalks and dead foliage act as overwintering shelter for many native bees and other beneficial insects. Birds also benefit from seeds and cover left through the winter.

According to renowned entomologist and ecologist Doug Tallamy, your goal should be to have all of the leaves that fall on your property remain there. In his book, Bringing Nature Home, Tallamy states that leaf litter can be home to an array of native insects while it is fertilizing, mulching, and watering your land. To keep your landscape looking tidy, edge your beds to create a neat separation of garden and lawn. This may be done using a good edging tool or by creating a border with rocks or some other type of edging material.

Fallen leaves should either be removed from your lawn or mowed with a mulching mower so that the grass is not smothered. Rake the leaves into garden beds or create leaf piles in out-of-the-way corners of your property where they can remain to decompose. Allow leaves to accumulate under shrubs. I pile oak leaves under my rhododendrons to retain moisture and act as a natural mulch.

You can rake them into garden beds, around tree bases, or into other designated areas. Leaves are great for soil quality: they can suppress weeds, retain moisture, and boost nutrition. And perennial plants appreciate the extra insulation through the winter, too!

Shredded leaves will not provide the same cover as leaving them whole, and you may be destroying eggs, caterpillars, and cocoons along with the leaves. Instead of a mower, use a rake or blower to keep leaves intact. If you use leaves for compost, consider creating a leaf pile and allowing it to break down naturally if space allows. Millipedes, roly-polys, and other leaf-eating bugs will help and enjoy the meal! You can also add the leaves gradually to your existing compost pile.

Leaves should be shredded only as a last resort because shredding causes a drastic decline in moth and butterfly numbers. You can rake them into garden beds, around tree bases, or into other designated areas. Leaves are great for soil quality: they can suppress weeds, retain moisture, and boost nutrition. And perennial plants appreciate the extra insulation through the winter, too!

Consider leaving most perennial flower stalks uncut through the winter. Many native pollinators overwinter in their hollow stems. The seedheads provide both winter interest and are also a food source for birds. Peonies, irises, and lilies should be cut back to a height of 3 to 5 inches and the foliage removed. Any diseased plants should be completely removed and bagged for disposal.

Vegetable gardens are an area where it’s especially important to clear away diseased plants and any dead or decaying plant material. Spread fallen leaves on your vegetable garden now in a 2-to-3-inch layer, which should decompose before spring planting. They will add organic material to the soil.

So, with fewer leaf removal chores, relax a bit and enjoy the colors and smells of fall!

More information about fall cleanup strategies

• Impacts of Leaf Litter Management On Insect Communities
• Leave the Leaves: Winter Habitat Protection
• Fall Garden Clean Up With Pollinators and Other Wildlife in Mind
• Tallamy, Doug. Home Grown National Park

Barbara Murphy is a Penn State Master Gardener. This volunteer program supports the outreach mission of Penn State Extension and provides research-based information on best practices in sustainable horticulture and environmental stewardship. For more information, contact the Penn State Extension of Allegheny County at alleghenymg@psu.edu or 412-482-3476.