Turning Autumn Leaves Into Healthy Lawns

Autumn is perhaps the most mellow and reflective season of the year. Shorter days encourage reading in the evening while crisp air and colorful vistas invite weekend hikes and trips to the countryside. Regrettably, too many people waste their precious weekends raking leaves into piles or shatter the quiet peace of sunny afternoons with leaf blowers. There is a better solution.

Rather than trying to rid your lawn of fallen leaves, you should actually consider leaving them where they are. It is nature’s way to recycle, after all. Certainly no one is raking up and bagging the leaves which fall in wooded parks and forests. Given a bit of time, all of the leaves are transformed by worms, bacteria and other organisms into rich humus, which will continue to feed trees, shrubs, and other plants year after year for millennia.

Your yard is simply an extension of the same natural process. Trees around your property draw nutrients and minerals from the soil, converting those elements into new leaves and branches. By raking up those leaves, you essentially short-circuit the natural cycle by which nutrients are returned to the soil. After a number of years, the soil will lose its fertility. In fact, carting off leaves and grass clippings is akin to strip mining, ultimately affecting the health of everything you are trying to grow.

Spreading costly fertilizers on your lawn may restore some nutrients, but not all of the vital minerals and organic matter needed for healthy, vigorous plants. Leaves, on the other hand, contain all of the nutrients and micronutrients your lawn needs. The trick is getting those leaves back into the soil without smothering your lawn in the process.

Enter the lawnmower. For the past ten years, almost all new lawnmowers sold have been mulching mowers. After decades of bagging clippings, a majority of homeowners have learned that it is best to “grasscycle” their lawn clippings when they mow. Clippings left in place quickly decompose and provide nutrients to keep the lawn healthy.

Your lawnmower can now do double-duty as a leaf-mulcher. Mower blades can easily shred whole leaves into small pieces, approximately one-tenth their original size. Your once-daunting bounty of leaves will disappear into a thin layer of tiny particles easily digested by worms and bacteria. In fact, a healthy earthworm population is capable of dragging a one-inch layer of organic matter down into their underground burrows in just a few months. Unseen by human eyes, they are diligently loosening and enriching your soil, and feeding the roots of your lawn for free. Perhaps you should think of your mower as a food processor for worms!

Begin your regimen of leaf-mulching by setting the mower to a normal three-inch height. Remove bagging attachments and block off the chute on a rear-discharge machine. Run your mower over the lawn while walking slowly, giving the mower blades plenty of time to shred up the leaves. Please note that mower-mulching works best when leaves are relatively dry and are no more than one inch deep. Do not wait until every last leaf has fallen before getting started.

If your mower has a side discharge chute, you will probably want to begin on the outside perimeter of your lawn, blowing your chopped leaves onto unmowed areas, and continue mowing inward. This will keep the leaf particles on the lawn, and even allow you to mow over them a few more times. Some savvy gardeners like to direct the discharge of shredded leaves into ground cover areas or under foundation plantings where organic matter is also welcome.

If your first pass over the lawn has left a significant quantity of whole leaves, go back over the leaves while mowing at a right angle to the first cut, perhaps walking even more slowly. Leaves take more work than grass, especially if they are somewhat damp.

There are other options and uses for some of your shredded leaves. For example, if your mower does have a bagging attachment, you might want to apply the shredded material as a mulch two to four inches thick under your trees and shrubs. Do not pile the mulch directly against tree trunks.

Shredded leaves can also be applied to other planting beds, such as perennial borders and herb gardens. Avoid applying mulch until after the first hard freeze. A two to three inch mulch layer will help maintain a uniform soil temperature all winter and protect tender root systems. The mulch blanket will also prevent frost upheaval caused by frequent thawing and refreezing, which is especially damaging to bulbs, tuberous flowers, and some half-hardy perennials.

Naturally, the leaf mulch will also feed your plants by recycling nutrients, conserve soil moisture during dry spells, and prevent the emergence of weeds.

You can also add your shredded leaves to a compost pile or bin. The smaller leaf particles decompose in about 75 percent of the time required by whole leaves, and you can further add a astonishing volume of shredded leaves into the bin, which is useful for properties with numerous mature trees. In addition, if you find that you are cutting some grass while running over the leaves, you are probably creating the perfect blend of materials to ensure an effective, fast-working compost pile. Your shredding efforts may even reward you with nutrient-rich compost ready for use in the Spring.

Copyright 2009, Joseph M. Keyser