Winter traditionally puts a chill on composting. Short, cold days allow conditions inside your compost piles to cool down to almost nothing. The supply of compostable materials from your landscape falls off once the leaves are raked and the freeze is on.
But composting doesn’t have to come to a full-stop during the cold months. Here’s how to care for your established, outdoor compost pile during winter, plus tips to start new ones, even in January. Like a lot of activities, composting can come indoors during the frozen months with help from Bokashi buckets and worm bins (vermicomposting).
First, know what you’re doing. A solid background in composting that includes understanding of green and brown material ratios, the best moisture conditions for making compost and other basic knowledge will go a long way in keeping your compost active during the winter.
Convert kitchen, yard and garden waste into soil-nourishing organic matter with our backyard tested composting bins and supplies. Need advice? Visit our Compost Blog for the basics and some insider tips from the pros.
Fall Prep: Winterize Existing Piles
- Collect all the leaves you can. Winter heaps need more brown material to stay active. Yet most of what you’ll be bringing out from the kitchen will be green.
- Bulk up the inside of the pile when turning the heaps in the fall. Leave as much air space inside as possible. This puff factor, like goose down in a jacket, helps with insulation. It also provides for oxidation — the decaying process — of the kitchen scraps you’re adding.
- Insulate your pile with fall leaves. They’ll help keep in the heat generated at the center of the pile. Straw makes a good cover if leaves are in short supply. To keep leaves in place, use a tarp or, like my grandfather and Stu Campbell, author of Let It Rot: The Gardener’s Guide to Composting did, cover the heaps with a burlap or old duck canvas cover. The fabric holds in heat and moisture and stays breathable, even when soaked.
- As the University of Wisconsin-Extension suggests in its piece on winter composting, leave a hole in the leaf cover at the top of the heap. That’s where you’ll pour kitchen scraps into the pile. Pull leaves from around the sides of the heap and add to the hole after adding green waste to make for good green-brown layering.
- Build a wind block of straw bales around your pile.
- Covering growing beds — or places where new beds will be sited — with sheet compost, famously known as the “lasagna” method is a horizontal, on-the-spot method of building better soil right in your garden. After the ground freezes, you can tuck your kitchen scraps under the cover. This makes for good green (scraps) and brown (straw) balance.
- Have more leaves than your piles and tumbler will accept? Bag them along with some green material — kitchen scraps or fresh mown grass — and let them overwinter, preferably in the sun. Black trash bags are best. They develop more heat in the sunlight. In the spring you can add the composting leaves from the bags into your piles or directly in your garden, depending on their condition.
Site and Design of Compost Piles
- Protect your piles with walls or some kind of break on the east, north and west sides. Keep the south side open to the sun for maximum warming. Site compost tumblers to take best advantage of the sun and protect them from the wind.
- Scoop out soil where the pile will be located to a depth of one or two feet. Being partly submerged in the earth helps keep the pile insulated and active.
- You’ll have to shovel a path to your piles in regions that see major snow accumulations. Keep your piles close and convenient to your back door, but not so close that they’ll be an eyesore come summer.
- Trenching — Storing your green waste in shallow trenches dug directly in your garden gets your scraps pile-ready come spring. This method gets the composting process started early especially in areas that experience frequent freeze and thaw cycles and may even yield finished compost if the ingredients are chopped finely enough. In cold regions, six to ten weeks in the ground may not be enough to have finished waste. When the daily temperatures begin to rise in March or so, dig them up and transfer to your piles/heaps or tumbler. You’ll have kept the microbes in your garden soil active and well-fed.
Winter Care of Compost
- Low humidity and winter winds, both problems here in the mountain west, can dry out your pile. Water it sparingly on a day when the moisture won’t immediately freeze as needed.
- Add only green kitchen scraps to your pile during winter and use large quantities — you can hold your scrapes in pails or buckets — when you do. Adding finished chicken or steer manure, blood meal, alfalfa pellets or other high nitrogen amendments will help keep temperatures and microbe activity up.
- As winter turns to spring and moisture increases, compost heaps may turn slimy and start to smell. This is a good time to add brown material — leaves if you have them left from fall — or dry sawdust.
- Compost tumblers: Turn your compost as frequently as possible. Add as much green material — kitchen scraps and the like — to keep whatever activity there is existent. In between, drape your compost tumbler with a well-anchored tarp that will insulate and serve as a wind-break. Locate your tumbler near landscape or buildings that block prevailing winds.
- If what’s inside your tumbler freezes solid, don’t attempt to turn it. There’s no need. It’s axles and pivots are probably too frozen to budge. And if you do succeed, sudden shifting of the heavy, icy block inside can damage the tumbler and, worse, the person doing the tumbling. Wait for the thaw.
- Make sure scraps are finely chopped. Don’t use rinds.
The All Seasons® Bokashi Bucket uses beneficial bacteria to quickly ferment organic table scraps into a nutrient-rich soil enhancer in just 2-4 weeks. Each kit includes a 5-gallon collection pail w/ spigot, a 1-gallon bag of starter mix, and complete instructions.
Bokashi is an anaerobic fermentation process that turns food scraps, including meat and diary into a soil amendment and a highly acidic, concentrated liquid that can be diluted and used to make compost tea. This liquid needs to be drawn off every day during the cycle. But other than that, Bokashi requires nothing more than packing the bucket with kitchen waste, sprinkling it with the bran or other carrier of the beneficial microbes and repeating until the bucket is full and sealed.
Oxygen is the enemy of anaerobic digestion and will slow the process. Tightly packing the materials and layering with the bran inoculant, as well as having a tight fitting lid, make things go more quickly. Your nose will be the first to know if the process isn’t going correctly. Bokashi’s recognizable sour smell will turn completely foul.
What to do with your “pre-compost” after the cycle is complete? Because of its acidity, finished bokashi needs to be kept from plant roots for two weeks and not used in a growing garden for a month. Adding it to your compost pile is a good solution during the growing season. Trenching it into your hibernating garden during winter is also an option.
Worm composting or vermicomposting puts the little red wigglers to work turning your kitchen scraps (with the exceptions of meat and dairy) into a soil amendment and worm tea that’s high in microbial activity. You can make your own worm bin or buy one designed to make the composting and collection of finished products easy.
What to do when winter gives way to spring? Worm bins can be used indoors or out, as long as the temperature isn’t lower than 55 degrees. You’ll also want to keep your outdoor worm bin out of the sun to prevent temperatures that will harm your wigglers (85 degrees and higher). Or just empty out the bin, worms and all, in your compost heap or garden.
Here’s more information on vermicomposting through the winter months from the fine folks at Michigan State University Extension, a place where they know what “cold” means.
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