Radical Acceptance: Winter Composting in the North

Listen, your backyard compost pile or bin will very likely freeze and cease composting this winter. We want you to know this now (especially if you are a new composter), with ample time to feel all your feels.

Breathe in this reality, and let your mind, body, and soul embrace this truth. You aren’t doing anything wrong, o’ sweet soil builder. It simply is. Love yourself. Love your pile. Do not suffer from unrealistic expectations!

While our radical acceptance is a bit playful, we mean it. Home composting is a fantastic way to use vegetative kitchen scraps and yard waste, keeping organic matter out of the landfill while making a valuable soil amendment. But it can be a bit discouraging to lose 4-5 months of composting time to Old Man Winter. Composting microbes generate heat as they chow down on organic materials, but small piles are no match for our sustained below-freezing temperatures.

The Minnesota Pollution Control Agency maintains a great website for basic home composting instruction and recommend a pile size of 5’ x 5’ x 5’ to prevent freezing in the core of the pile. The hitch? Smaller piles may be more desirable for many reasons including available space, neighborhood aesthetics, pest control, and more. Always check your city or town solid waste ordinances to ensure you know the rules.

Once small-pile owners have gently released any expectations for year-round composting, know it is possible to continue to collect material in the winter months and ready the pile for a hot-n-healthy spring startup. First, save up carbon for the long cold season. Popular carbon sources (also known as “browns”) include leaves and dried grass clippings. Store enough carbon so that you can add “browns” to the pile in about equal volume as vegetative (“greens”) material with each deposit. You may choose to have a compost set up with built-in carbon storage bin, or simply keep a few bags of leaves at the ready.

Be sure you have the capacity to add material during the winter months. This might mean emptying all the finished compost from the bottom of the pile at the end of the growing season to free up space. Then proceed as usual, adding the “green” vegetative scraps from the kitchen and covering with a blanket of “browns”. Winter composting requires maintaining access, so keep a path clear of snow.

Cutting your “greens” into smaller pieces will give more surface area for decomposition when they eventually thaw and may buy some valuable time. Place the pile in a sheltered, sunny area to help with heat retention; some composters find black bins or covers encourage the temperatures to climb faster. As spring creeps in, monitor your pile for moisture as it likely dried out during the winter. Add enough water so the thawed material is universally damp but not wet. Stir the pile once or twice a week to aerate it as soon as you are able. Stirring ensures the microbes have the needed oxygen to break the material down and helps perk them from their dormancy.

With a little planning and an open heart, northern composters can make the most of chilly circumstances.

At WLSSD, our large-scale compost piles are actively composting 24/7, year-round. The carefully crafted windrows are aerated to provide microbes plenty of oxygen throughout the pile, and temperatures soar up to 160 °F even in the bleakest of cold snaps. High temperature composting means we can also accept meat, bones, and dairy products that don’t belong in a backyard pile.
Residents can participate in our drop site program (see below) anytime, steward their own compost piles, or use both approaches. The rich results enliven both soils and spirits.