The Benefits of Fallen Leaves
By Kathleen Cue, Nebraska Extension Horticulture Educator
It’s too bad autumn’s fallen leaves are seen as a nuisance, something to be gotten rid of as soon as possible. In truth, they are a boon to landscapes, serving as mulches, benefiting soils, and boosting our compost piles. Not only are leaf piles fun to jump in and make for great leaf fights, by using leaves, we keep this resource out of landfills.
Mulching leaves into the turfgrass with the mower is one easy option. The ideal amount of leaf mulch is enough so that bits of leaves filter between the blades of grass. More than this can suffocate the turf, contributing to snow mold damage over the winter months. With my electric mower, I can start the engine while the mower deck is directly over the pile. This makes quick work of a large pile into a usable mulch. A leaf blower with a vacuum/mulching function does equally well, allowing for the bagging of shredded leaves to use elsewhere.
Shredded leaves can be used for mulching perennial flower beds, shrub borders, and over tree roots. A 2 to 3 inch layer is ideal and will protect plant roots over the winter months. The fallen needles of evergreens are also excellent mulches and can be left in place. Over time, they will acidify the soil, creating the soil conditions that conifers prefer.
One nutrient in high quantity in fallen leaves is carbon. Most people are familiar with nitrogen as the main ingredient in most fertilizers, being unaware that plants use carbon in much higher quantities than nitrogen. Typically, plants readily take in carbon dioxide from the air, but root uptake of carbon from the soil also happens. A soil with an abundance of carbon will be dark and earthy, providing spaces for plant roots. Shredded leaves are an excellent addition to soils for vegetable and annual flower gardens, as well as preparation for new gardens. Giving the garden a quick rough turn with the potato fork will incorporate leaves, ensuring they won’t blow away and will begin the process of decomposition.
Compost piles work most efficiently when they are composed of both green (fresh) and brown (dried) materials. During the growing season, it’s easy to add an abundance of green materials to the pile. By incorporating autumn leaves, however, the compost pile will decompose more efficiently, resulting in a better end product.
When leaves are composted by themselves, the end product is leaf mold, which is highly prized by gardeners. I inadvertently made leaf mold when I left a bucket outside one winter. Leaves collected in the bucket and with the added moisture from rain and snow, by spring I had this wonderful crumbly stuff that got added to my potted plants. It made for happy plants!