Post Season Utilities by Fallen Leaves

Fallen leaves can be used for improving the garden soil as well as for providing winter protection for some plants. If not removed promptly, leaves may smother grass and other small plants, especially if they become wet and compacted. A few leaves on the lawn do not create any major problem. These can be chopped up as the lawn is mowed and caught with the clippings.

Large quantities of leaves left on the lawn, however, form a tight mat that can exclude light and air from the grass. If left on the lawn too long, dead or thin spots can develop in the lawn. Leaves are best used to make compost for improving the soil. However, there are a few situations for which leaves can be as beneficial as a mulch in protecting some tender plants during the winter.

The best leaves for mulch are those that are stiff and slow to decompose. Oak leaves are one of the best for this use. Because they are sturdy, they do not pack tightly around plants. They are particularly useful for a mulch around large plants with shallow, fine root systems such as azaleas and rhododenrons. Soft leaves, such as those from maple, ash and trees, tend to mat more readily and thereby interfere with air movement in plant roots.

When leaves are used around plants they should be enclosed in wire cylinders to keep the leaves from blowing away in mid-winter, thereby exposing plant stems. They may be used around the base of a plant, but should not cover the foliage at the base of an evergreen plant. Leaves are put to good use as a source of organic matter for a compost pile. Leaves in themselves cannot be considered high in fertility.

The plant withdraws a major amount of starches, sugars and plant nutrients before the leaves are dropped. Therefore, leaves are slow to break down when added to the compost heap. Fallen leaves are largely cellulose, but it is the cellulose that makes them excellent soil conditioners after they have decomposed. When making compost from leaves, the addition of other materials to speed compost is helpful. Chopped leaves are also quicker to decompose than whole ones. Leaves should be layered with soil to introduce organisms that begin the breakdown process.

Garden Soil, Improving Your Garden Soil, by Ortho Books.