Put Fallen Leaves to Work

If fallen leaves are not promptly removed, they smother grass and other small plants. Fallen leaves should be put to work at the jobs they do best: improving soil and providing winter protection from some plants.

A few leaves on the lawn do not create a major problem. They are chopped up as the lawn is mowed, and caught with the clippings. Large quantities of leaves, however, left on the lawn form an impervious mat as they settle together and exclude light and oxygen from the grass. If leaves are left on the lawn until spring, areas can be found where grass has been weakened or completely killed.

Are leaves more suitable for a mulch or for compost? Generally, leaves serve their best use as compost. As a mulch they are difficult to keep from blowing away, thereby losing some of the protective depth required. Oak leaves are generally the best leaves for a mulch. They are slower to decompose and are sturdier so they do not pack into a tight layer. They are particularly suited for a mulch around large plants with shallow, fine root systems such as azaleas and rhododendrons. Soft leaves, such as those from maple, ash and poplar tend to mat more readily and interfere with air movement to plant roots.

Leaves in themselves are not high in fertility. The plant withdraws a major amount of starches, sugars and plant nutrients before leaves are dropped. Therefore, leaves are rather slow to break down when applied to the compost heap. Fallen leaves are largely cellulose, and it is the cellulose that makes them excellent soil conditioners once decomposed. The addition of other materials to the compost heap seems to speed their breakdown. Sources of starch, stale bread, spoiled flour, meal or similar materials supply food for the rapid development of microorganisms to help break down the leaves.

The leaves must be layered with soil, which introduces the organisms that begin the breakdown process. In addition to these materials, nitrogen must also be added. About four ounces of actual nitrogen are needed for each bushel of packed leaves. This would mean about 12 ounce or ¾ cup of ammonium nitrate.

If a general garden fertilizer is used, such as a 12-12-12, about two lbs. is needed to supply adequate nitrogen. Mix the compost in a few months or early spring, and keep it moist at all times. When there is no space for a compost pile, leaves can be turned into compost directly in plastic bags. Make sure that the leaves are well wetted and that adequate amounts of fertilizer and soil have been added to each bag. Layer these materials as in making a compost heap.

Where space or times does not permit composting, a limited amount of leaves and other organic matter can be applied directly to the garden soil. The material should be sprinkled with fertilizer and promptly plowed under. Next season, plants may develop a temporary nitrogen deficiency as a result of this practice, so be prepared to watch for the problem. If plants appear stunted or starved, a nitrogen sidedressing should be applied promptly.

Mac Perry's Florida Lawn and Garden Care, by Mac Perry.