Over the Garden Gate: Managing fallen leaves

Along with all of autumn’s glory comes the work of attending to the fallen leaves.

Have you wondered if there is a better way of managing them? In years like this when we get an early snowfall, should that impact your approach? Should you treat your lawn differently from your gardens?

Ecologically, leaves are beneficial to soil health as they return nitrogen to the soil as they decompose. However, aesthetic considerations and the risks of plant diseases create the need to address fallen leaves more proactively, but that does not mean you want to remove them completely.

A heavy layer of leaves can smother your lawn, restricting new growth in the spring. Diseases such as snow mold are more likely to develop in compacted leaves; the main diseases being Microdochium patch caused by Microdochium nivale, Typhula blight caused by Typhula incarnata, Coprinus snow mold caused by Coprinus psychrombidus and snow scald caused by Myriosclerotinia borealis.

Some tree diseases overwinter on fallen leaves such as anthracnose on oaks (Apiognomonia quercina), dogwood (Discula sp), and sycamore (Apiognomonia veneta), and septoria leaf spot (Septoria cornicola) on dogwood (Cornus spp.) If you know your trees have those diseases, the presence of pathogens can be reduced by raking the leaves under those particular trees and destroying them.

For the majority of leaves on your lawn, consider recycling them in place for the benefit of your grass. This works best if done in several installments as the leaves fall, instead of all at once. If your power mower has a mulching blade, this would be the time to use it, but even the standard blade will work to cut dry leaves into small pieces that will break down more quickly.

Consider taking the next step of light nitrogen fertilization (about 1 pound of nitrogen per 1,000 square feet of grass) to help speed the decomposition of the leaves and prepare your lawn for spring, but not after the first frost of the season when it can do more harm than good.

Your garden beds can also benefit from fallen leaves, increasing the organic matter available to healthy plants in the spring. As with your lawn, a heavy cover of wet leaves all winter is detrimental, but shredded leaves turned over into the soil with a spade, are good. If excess shredded leaves are on the grass, you can collect them and add them to your garden beds.

Shredded leaves can also be used as a winter mulch to protect perennials through the coming winter weather, avoiding thick layers, but instead applying a 3- to 6-inch layer of shredded leaves on and around tender perennials after the cold weather returns. The goal of winter mulch is to keep plants dormant through the winter, so it must be applied after the ground is cold and plants are fully dormant, sometime between the Thanksgiving and Christmas holidays.

Timing is important, so think through your strategy as early as possible, be ready to mow when the leaves are dry, add nitrogen before the frost, and consider a sheltered space to store extra shredded leaves until it is cold enough to put them on your perennials. Come spring, you will be rewarded for your efforts.

Katie Klaber is a Master Gardener trainee with Penn State Extension — Beaver County.