'Tis the season for harvesting leaves, the most abundant free source of organic matter available to most gardeners. Microorganisms in soil and compost transform leaves into bits of organic matter, which helps the soil retain nutrients and moisture. By themselves, leaves contain small amounts of 16 plant nutrients.
You can stockpile leaves in a bin or pen to use later as compost or mulch, but you don't have to wait until leaves decompose to put them to work. With some shredding assistance from your lawn mower, you can give your leaves useful jobs right now.
1. Turn lawn into garden. Prepare sections of lawn you want to develop into garden beds by smothering them with leaves. First scalp the grass by mowing as close to the surface as possible. Then cover the space with several thicknesses of newspaper or cardboard, and cover the base layer with two inches (or more) or compost or manure. Top with 3 to 4 inches of shredded leaves.
2. Winterize hardy vegetables. Use shredded leaves to limit winter injury to kale, leeks, carrots and other hardy vegetables. Surround the planting with a low fence or burlap enclosure and fill it with up to 12 inches of shredded leaves. Mulch garlic and perennial onions with up to 6 inches of shredded leaves mixed with the season's last grass clippings.
3. Bury them in a trench. Improve the drainage and organic matter content in garden beds by digging narrow trenches, filling them with shredded leaves, and then covering them up. By late spring, the leaves will be sufficiently decomposed to mix into the soil, or you can plant right into the enriched trenches.
4. Mulch-mow them into your grass. Research done at Michigan State University reveals that when rather thick layers of leaves (to 12 inches) are shredded with a mower and allowed to rot where they fall, the grass greens up faster in spring and grows better the following summer. Just don't expect the leaves to disappear from view until the grass starts growing next year.
5. Mulch your trees. Stockpile shredded leaves until early winter, and then tuck in trees, shrubs, and perennial beds with 3 to 4 inches of shredded leaf mulch. A thick leaf mulch helps moderate soil temperatures in winter, reducing cold-related injuries to shallow roots. Beneficial soil-dwelling fungi are also abundant beneath shredded leaf mulch – one reason why Colorado State University lists mulching among its Ten Commandments of Planting Trees.
There is one precaution: Be careful with black walnut leaves, which can cause reduced growth in many plants, including tomatoes. According to Iowa State University, the juglone in black walnut leaves is usually neutralized by 4 to 6 months of composting.
Do you have other leaf-handling methods that work great at your place? Be sure to share them in the Comments section below.
Contributing editor Barbara Pleasant gardens in southwest Virginia, where she grows vegetables, herbs, fruits, flowers and a few lucky chickens. Contact Barbara by visiting her website or finding her on Google+.