Every fall, tall bags of leaves line our street as diligent homeowners “clean up” their yards.

In nature, leaves decompose on the forest floor and add nutrition to the soil. When I see someone carting off all their leaves, I can think only of the nutrients in those bags that aren’t getting to the plants in the yard.

Always on the lookout for ways to enrich my soil, I started suggesting to some of my neighbors that they save themselves a trip out to the city compost site and drop their leaves at my place. They think I’m a little nutty, but they would think that anyway, even if I didn’t eagerly collect their leaves each fall. In my opinion, you’re a little nutty if you let all that valuable material leave your property, so the feeling is mutual!

I have a very small yard, so donations from a few neighbors plus our own leaves are about all I can handle. I use some to mulch plants for the winter, which protects the soil from erosion, shields the plants from the cold and discourages weeds while adding nutrients and conditioning the soil.

I also make sure to put some big bags of leaves by the composter so I can add these crucial sources of carbon to balance a typical ‘nitrogen-heavy’ winter compost. When spring comes, the leaves removed from the garden beds also head right over to the composter to help maintain the balance of nitrogen and carbon throughout the season.

Why keep your leaves?

  • Retaining raked leaves keeps nutrients on your property. Why buy fertilizer when you can make your own?
  • Leaves are a good source of the minerals growing plants need. Plus, they aerate the soil and improve drainage.
  • Leaves are free mulch!
  • Leaves are a great source of the brown material that you need to compost successfully and efficiently, particularly in winter. They also help you make more compost overall. This means free food for your soil in spring when it’s most needed — and no plastic bags of compost of unknown origin from the store.

Winter composting 101

Some people stop composting their food scraps in winter, but there’s no need. In our super-cold Minnesota winters, compost piles freeze through and decomposition grinds to a halt. But if you’ve made sure to empty your bin, there’s plenty of room for an entire winter’s scraps layered with leaves.

When the compost defrosts in spring, you’ve saved all those great nutrients for your garden. I don’t know about you, but when you’re used to composting, it’s painful to watch nutrient-filled food scraps being thrown in the trash to be wasted and create methane in a landfill!

If your winters are not so extreme, you can take steps to keep the compost warm enough to keep chugging along year-round.

Keeping compost warm

If possible, move the composter to a sunny spot in your yard. You can also insulate it with leaves or straw, or even snow! If you have a greenhouse, the composter can be kept warm by moving it in there, while the microbial activity of the compost will help heat the space as well.

An insulated compost tumbler is an effective way to speed up composting throughout the year. In winter, the rotation of the tumbler keeps the compost aerated and the composting process active, creating heat. The sides are insulated to keep out the cold, and it’s elevated off the cold ground. Bonus: Compost tumblers are inaccessible to critters, reduce odor and you never have to turn over a compost pile. And it’s easy to decant finished compost – just park your wheelbarrow beneath the unit, open the tumbler doors and spill out the compost into the wheelbarrow.

Successful winter composting requires leaves

One of the tricks to successful winter composting is planning ahead to have carbon sources handy, since you’ll be adding fresh food scraps (nitrogen) from your kitchen through the cooler months.

If you don’t have enough “browns” (carbon) to balance out all those “greens,” the balance of nitrogen to carbon will be off and you’ll have wet compost that doesn’t break down into the gardener’s “black gold” our plants crave. Leaves can also help revive a soggy compost pile if your pile got too wet, or had too many greens in it.

Which leaves are best?

Most leaves will be fine for your compost, though some leaves break down more quickly than others. Some of the most useful leaves come from maple trees, as they aren’t very acidic and break down quickly, unlike more acidic oak leaves, which also take a longer time to decompose. Most leaves are at least somewhat acidic, so if you’re using large quantities of leaves in your garden, it would be wise to test your soil.

Leaves to avoid when composting

Certain trees — black walnut, butternut, and to a lesser extent, hickory — produce a compound called juglone, which can cause sensitive plants to wither and die. If you have a black walnut on your property, you’ve no doubt learned to give it wide berth for all but the most juglone-resistant plants.

Some sources say that juglones in leaves break down in contact with air and microbes, and that composted leaves should not pose a threat to your garden. If you prefer to err on the side of caution, you might keep large quantities of leaves from these trees out of your compost. If you’re getting donations from neighbors, be sure to let them to know to keep the walnut and hickory leaves from the bags they’re giving you. Eucalyptus leaves also contain a compound that interferes with germination, so best to leave them out of your compost as well.

How to keep and use your leaves

Collect leaves on a sunny day once they’ve dried well. Store in a breathable bag or container and put it near your compost, making sure to protect it from the rain. Mix leaves in when you add food waste throughout the winter. The rule of thumb for compost is ⅓ green to ⅔ brown, so as you add food waste from your kitchen, grab a few handfuls of leaves to cover the kitchen scraps.

Shredding your leaves

If you have a lawn, you might want to run a mower over them to shred the leaves a bit. This helps with the problem of matted leaves that prevent the aeration you need for successful composting. You might also see if someone in your neighborhood has a leaf shredder they’d like to share with you.

If you don’t have the means to shred your leaves, it’s wise to crumble them a little as you add them to your compost to help prevent matting.

Too many leaves?

If you have far too many leaves (lucky you!), you can try leaf composting which involves layering leaves with soil. Less full of nutrients than compost made from food scraps, the finished leaf compost is still a valued soil conditioner.

Get the kids to help

Most kids love collecting leaves, whether for jumping, art projects, or just for observing the wonders of nature. When they’re done leaping in your leaf piles, involve them in the work of readying the garden for winter. Kids can help tuck in plants with leaves and bag the ones headed to the compost. It’s a great way to teach them about plant cycles, caring for a garden, and soil nutrients.

When the big bags come from our neighbors, we get to see the variety of leaf shapes, from the ubiquitous maples to the elegant gingkos from down the block. Even preschoolers quickly become adept at recognizing different leaf shapes. Fall cleanup becomes a pleasant time to learn about and enjoy the natural world, even in a small urban yard.

Gather up those leaves now to help your compost keep humming throughout the winter!

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