Q: What can I do with all the fallen tree leaves in my yard? There are so many!

A: Although those leaves may seem like a nuisance, try to consider them as a valuable resource provided free by nature. Leaves, with some patience but very little effort on your part, can be turned into an excellent soil amendment or mulch you don’t have to buy.

It seems strange that, in the fall, we rake leaves to put into plastic bags to be hauled away for disposal somewhere else at a cost to us; and then in the spring, we spend more money on plastic bags of mulch or compost to add to our garden. If you have the leaves available, why not use what nature provides to restore the natural process of plant nutrient recycling in your yard?

There are two basic approaches to recycling leaves. One is mulching the leaves into the grass; and the other is piling the leaves to transform into leaf mold.

For the first approach, your lawn mower is the only tool needed. A mulching mower works best; but a regular mower will do the job, although not quite as effectively. Simply mow over the leaves on the lawn to shred them, walking slowly to give the mower blades time to chop the leaves.

This is easier to do if the leaves are relatively dry and not piled too thickly, so don’t wait until all the leaves have fallen to start mulch-mowing them. You may need to go back over the leaves in a cross direction from the first cut to shred the leaves more finely.

Shredded leaves decay much more quickly than whole leaves. The small leaf pieces on the lawn break down, adding organic matter and returning essential plant nutrients to the soil to be taken up by the grass. Research conducted at Michigan State University in the 1990s found no negative effects of mulching leaf litter into the turf. The quality of the grass improved, with fewer broadleaf weeds; the quality of the soil improved, even to the extent of providing a softer surface for sports; and it had no effect on the soil pH, whether oak or maple leaves were used.

If you end up with a pile of these shredded leaves, you can also apply them as a 2- to 4-inch-thick layer of mulch around trees and shrubs, or on perennial beds, being careful not to mound them right against the trunks or stems of plants. The leaf mulch will help to moderate soil temperatures, retain soil moisture and keep down weeds. Weeds that do appear are easier to pull because the soil surface remains friable and soft.

The second method of recycling leaves is turning them into leaf mold. Basically composted leaves, leaf mold is similar to compost; it is dark brown in color, with a pleasant earthy smell and a crumbly texture. Although it is not high in nutrients, it is an excellent soil amendment that improves the structure of the soil, increases soil water retention, and stimulates beneficial organisms in the soil such as earthworms and bacteria. It can also be used as mulch or added to potting soil. And unlike compost or manure, leaf mold is mostly weed-free.

To make leaf mold, form a pile of leaves, pack them down, water them and wait a couple of years. Although not essential, a wood or wire bin, 3 to 6 feet in diameter and at least 3 feet in height, helps keep the leaves contained. You can speed up the process to 6 to 12 months by shredding the leaves; by turning the pile occasionally; by adding water occasionally; or by covering the pile with a tarp; but it will happen eventually even if you do nothing.

If you have a compost bin, you may have too many leaves in the fall to fit in the bin, so stockpiling those leaves in a separate pile is a good way to save this valuable resource. In the spring and summer, you can transfer some of your leaf stockpile into your compost bin as you need “brown” materials to layer with fresh “green” materials; the remainder of the leaf stockpile will gradually shrink in size as the leaves slowly decay to form leaf mold.

To a gardener, autumn leaves on and off the tree are not just pretty, they are a gift of nature waiting to happen.

Annette MaCoy is the consumer horticulture extension educator and master gardener coordinator for Penn State Cooperative Extension in Cumberland County. If you have garden questions, contact Annette at 240-6500 or by e-mail at ahm11@psu.edu.