The temperatures are falling — and so are the leaves.
While we can’t do anything about the falling temperatures, getting rid of the leaves is a priority. Rather than getting rid of leaves, put them to use in the garden, the compost pile and on the lawn.
Yes, the lawn. Shredding dry leaves with a mower adds valuable organic material to the lawn and might spare you from blisters or a thrown back.
Research at Michigan State University and Purdue University confirms what many seasoned gardeners already know: mulching leaves feeds the lawn and improves soil by adding nutrients.
Using a rotary mower to chop up leaves “has no detrimental effect on turf health,’’ Purdue researchers said. “In fact, the mulched leaves may improve soil conditions.’’
I was skeptical, to be sure. But I started mulching leaves, rather than raking, more than 15 years ago. Turf and flower beds covered in shredded leaves have done wonderfully.
MSU research bolsters the case even more: mulched maple leaves — particularly from sugar maples — help tame the spring outbreak of broadleaf weeds such as dandelions.
Remove the grass catcher from your mower, raise the mowing height and take a few passes over the leaves. The goal is to reduce leaves to dime-size pieces. If leaves are ankle-deep, spread them out so the mower can chop them up in two or three passes.
Once a half-inch of grass pokes through the leaf layer, you know you’ve got them chopped enough. Over time, worms, microbes and other lawn-dwelling insects will break down leaves and return nutrients to the soil.
Mulching oak leaves is fine — it doesn’t make the soil acidic. And even if it does, so what? Soil in many home landscapes tends to be alkaline, so a little acidity doesn’t hurt. But an MSU study determined that mulched oak leaves, once broken down, are pH neutral. The only drawback is that oak leaves take longer to break down than maples, aspens, and many other leaves. By mid-May, even an inch layer oak leaves will have disappeared into the soil.
Mulching leaves into the lawn will not cause thatch build-up. I’ve done it for years and find the thatch layer actually is lower than in areas where there are no leaves to mulch. For several years, I’ve collected leaves from other yards to use in areas of my landscape that were tree-free.
I’m in good company. Scott Meyer, the former publisher of Organic Gardening Magazine, told me a few years ago that looting leaves from neighbors isn’t as bizarre as one might think.
“You’re not alone; we know a lot of people who do it,’’ Meyer said. “It’s an incredible resource just falling at your feet.’’
Vegetable gardens like slightly acidic soil, so mulching them with pine needles is a better alternative to bagging fallen needles, Meyer said.
There is a caveat: Leaves are packed with carbon, and carbon doesn’t break down quickly without a little help. The help in this case is nitrogen — specifically, a fall fertilizer heavy in nitrogen.
There are myriad brands of fertilizer, but finding them after mid-October is increasingly difficult as Christmas displays elbow out fall lawncare products.
Fertilizers that use the term “winterizer’’ or something similar, such as Scotts Turf Builder Winter Guard, will help break down mulched leaves. Even though the grass is done growing, microbial activity continues until the ground freezes. Indeed, a late-season feeding is perhaps the most important of all. It helps roots develop until the ground freezes. Nutrients stored in the roots are available in spring for a quick green-up, which also helps crowd out weeds. And the kick of nitrogen feeds microbes as they work diligently to break down shredded leaves to bolster the soil.
Using woodchips, shredded bark or shredded leaves as a mulch around trees, shrubs and kitchen favorites such as asparagus, strawberry, rhubarb and raspberry is a time-honored tradition. It bolsters the soil, retards weeds and keeps soil hydrated and cool during periods of drought and heat.
There is a drawback, however. Apply mulch too thick and it will form a mat that makes it difficult for air and water to penetrate. It also can lead to anemic-looking plants unless you add a nitrogen-rich fertilizer before heaping on the mulch.
Soil microbes target mulch and monopolize available nitrogen for their growth and reproduction. That’s all well and good, but the nitrogen monopolization leaves plants crying for food. Add a little bit of nitrogen-rich fertilizer to the ground before covering it with mulch, and you will be OK. So will your plants.