Yard & Garden News

Fall Leaves Are Treasure, Not Trash

Tuesday, September 17th, 2019
Fall Leaves

Wet Leaves on campus
Photo Credits – Purdue Agriculture

The hot dry weather experienced throughout much of Indiana in late summer is bringing an early leaf drop to many landscape plants. But even under the best weather conditions, the shorter, cooler days of autumn signal deciduous plants to begin their color change and eventual leaf drop. For some, this marvel is overshadowed by the chores of raking and disposing of leaves.

What’s needed here is an attitude adjustment! Autumn leaves don’t have to become trash. On the contrary, they easily can be turned into valuable soil-enhancing organic matter. There are several ways to manage tree leaves at home.

Green-thumbed gardeners long have known the value of recycling plant material. Dry leaves can be plowed or tilled under in the vegetable or annual flower bed in fall to provide a source of organic matter. Shredding the leaves first will speed the breakdown so that the leaves will not be visible by spring. Be sure to mix the leaves into the soil, rather than leaving them on top through the winter, to avoid keeping the soil too cold and wet to work in the spring.

Tree leaves can be recycled directly on the lawn. Use your power mower or shredder/vacuum to break dry leaves into smaller pieces. A mulching blade on the mower will speed this process, but even a standard blade will do an adequate job. For large leaves, such as maple and sycamore, it may take several passes to get a finely shredded product. Once the leaves are pulverized, they will break down quickly. A fall application of nitrogen fertilizer (about 1 pound of nitrogen per 1,000 square feet) will help speed decomposition of the leaves and also will benefit the grass plants.

Fall leaves also make great composting ingredients, especially when mixed with green trimmings and grass clippings. Again, the smaller the pieces, the faster they’ll break down, so shred or chop dry leaves before adding them to the compost pile. If you don’t have green trimmings or grass clippings, add a source of nitrogen to the leaves, such as commercial fertilizer or dry cow, horse, sheep, or poultry manure. The nitrogen is needed by the microorganisms that break down the carbon in plant materials. Add a sprinkling of soil or finished compost to introduce a source of the microorganisms, and water just enough to moisten. The compost will heat up in the center as it breaks down. Stir the contents occasionally to add air and allow for uniform heating. Generally, the more often you turn the pile, the faster you’ll get a finished product. Compost is ready to add back into the garden when it looks uniformly dark and crumbly. Compost improves soil aeration, moisture retention and drainage, and nutrient-holding capabilities.

Last, but not least, shredded leaves can be used as a winter mulch to protect tender perennials through the coming harsh weather. Shredding the leaves will help prevent them from packing down as they get wet and smothering the plants that they are supposed to protect. To provide winter protection, apply a 3-to 6-inch layer of shredded leaves over the top of tender perennials after several hard freezes. The goal of winter mulch is to keep plants dormant through the winter, so it must be applied after the ground is cold and plants are fully dormant. The timing of application will vary from year to year with the weather, but most years will be appropriate sometime between the Thanksgiving and Christmas holidays.

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Author: B. Rosie Lerner, rosie@purdue.edu
Editor: Charles Wineland, cwinelan@purdue.edu
Category: Extension, Horticulture & Landscape Architecture

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