Do you love the colorful trees of fall but dread the aftermath? All of those heaps and bags of leaves can seem never ending. Instead of hauling them to the curb, its easy to compost leaves so they can benefit next year’s garden. Here’s where to begin:
Why leaves make great compost
Trees pull nutrients from deep beneath the surface and many of those nutrients end up in their leaves. Adding those leaves to your compost pile ensures that your compost will contain nutrients that garden plants can’t typically reach on their own.
Many of the ‘ingredients’ commonly used in making compost are high in nitrogen. These include kitchen scraps, manure, grass clippings, and similar moist green materials. Leaves are high in carbon and help balance out all of that nitrogen. Other high carbon materials include shredded paper, sawdust, wood chips, straw, hay, and dried grass.
According to experts at Cornell University, you should aim for about 30 parts carbon to every part nitrogen by weight.
How to compost leaves
Adding freshly shed whole leaves to your leaf compost pile or bin will likely create a matted, slimy mess that takes a long time to turn into usable compost. Normally, composting is an aerobic process where oxygen-loving bacteria and other microbes break down organic materials. When wet materials become matted in layers, anaerobic bacteria take over. They do the same job but in a totally different (and very smelly) way.
The way to avoid anaerobic decomposition is to chop large, generally flat leaves into much smaller pieces using a lawnmower or leaf shredder. That way the leaves can’t mat as easily and you’ve given the microbes a lot more surface area on which to get to work. You’ll also reduce those massive volumes of whole leaves into a much more manageable amount.
Leaves as mulch
Chopped leaves tend to stay put better than whole leaves since there’s less surface area for the wind to catch. Whole fresh leaves that don’t blow away will mat down and create a barrier that’s impermeable to water and air. That isn’t good for the plants you’re trying to protect!
According to garden writer David Beaulieu, “Leaf mulch is just leaf compost waiting to happen.” That’s why it’s a good idea to store bags of dry leaves in a shed or lean-to until spring. As long as they’re dry and crackly before you bag them, and stay dry in storage, they’ll be ready for mulching your flower beds and garden next spring. Storing moist leaves in ventilated black plastic bags will produce mulch in the form of rich, moist leaf mold. Why not try a few bags of each?
What to avoid when using leaves as mulch
Some leaves contain toxins that keep other plants at bay or even kill them. Not something you want to use in your planting beds! For this reason, don’t use leaves from black walnut trees in your vegetable garden. Butternuts, hickories, pecans, and English walnuts also contain the juglone toxin.
Insulating plants with leaves
A thick layer of insulating leaves can protect plants from erratic temperature changes in the winter. Even plants that are perfectly hardy in your growing zone can die if they’re tricked into breaking dormancy too early by a warm spell or if you suffer unusually cold temperatures. Leaves will help keep them uniformly cold throughout the winter.
For perennials that aren’t reliably hardy in your area, a warm blanket of insulating leaves can be the difference between life and death. Pile the leaves thickly around, between, and over them. It helps to create a temporary wire fence that will hold the leaves in place.
Frost-tender perennials will need more care to survive. Put a thick layer of leaves in the bottom of a plastic tote or sturdy cardboard box. Add pots of tender perennials that are dormant, packing more leaves around and between them. Then cover everything with as many chopped compost leaves as you can and seal it up. Place in an unheated garage or shed where they will stay cool and dry. Just don’t forget to unpack them next spring!
Composted leaves benefit next year’s garden
Leaves will attract earthworms that will help break the leaves down into beneficial leaf mold. As an added bonus, the worms will till your soil into the loose, friable mixture plant roots love! Leaf mold and compost help create the perfect garden soil: nutrient-rich, loose, friable, and well drained. It’s also an attractive, moisture-retentive mulch.
You’ll have even more reason to enjoy those gorgeous autumn leaves now that you know how beneficial they’ll be in your garden!