Winter Composting 101
A healthy compost pile can be a continuous source of fertilizer and soil mix throughout spring and summer. But what happens when cold winters hit? Here's how to make sure the compost pile you've built up can survive cold temperatures.
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Build Up Your Pile
Keep your compost "active" with microbes by building it up in preparation for winter. A good compost pile will be about a yard in diameter: If you have extra scraps and leaves, this is the time to start adding them in and expanding your pile as much as you can.
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Create More Insulating Space
The cold will threaten active compost microbes, if it can reach them. So create an insulated pocket of air in the middle of your compost pile by pushing decomposing matter to the sides. When covered, this air will stay warm while also providing necessary oxygen. Caring for your compost in the winter will allow you to amend your garden easily in the spring.
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Add Your Autumn Leaves
Composting is a great way to reuse and recycle yard waste such as autumn leaves and straw. Plus, they benefit your winter compost pile. They can help create an insulating outer layer that also provides some moisture protection when the snow falls. And add these leaves when you are finished with your winter yard work. You can also use fallen leaves a mulch.
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Keep Precipitation from Settling In
Precipitation on the top of your compost pile is particularly dangerous in winter, when it can freeze or leak down into the more vulnerable, active core. So if you already have a covered compost bin, make sure the lid is well-sealed. And for open air compost, consider building a covering or roof. Note that snow is dangerous when it starts to melt on top of compost, but snow built up on the sides will provide additional, useful insulation.
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Shelter Your Compost from Wind
Strong winter winds can disrupt and chill your compost. So keep your pile sheltered on three sides. Leave the side that gets the most sun open so the pile can warm up on clear days. Compost tumblers and bins can help protect compost more easily in high winds, but you should consider covering them with a tarp. You can make your own compost tumbler out of a polyethylene drum.
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Keep Feeding Your Compost
Compost piles can become starved of nitrogen over the winter. And adding greens and scraps throughout winter is important to keep the chemical balance healthy. However, keep the outer "brown" layer thick and dominant to avoid too much growth in this delicate time. Know which things you can compost and keep the greens-to-browns ratio balanced. If you don't want to make the trip outside in the winter, you can create a countertop compost station.
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Have a Ground Pile? Dig it In
If you have few shelter options, dig your ground pile into a trench a couple of feet deep. Also, this helps protect it from the cold and wind while also making it easier to mix the results with fresh soil in the spring.
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Avoid Large Compost Additions
Go easy on larger scraps over the winter. They provide less insulation than finely chopped compost pieces. For example, you want to keep large rinds out of the pile during the winter months. Some kitchen scraps can be used in the garden without being composted.
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Let the Freeze Pass
If the worst happens and your compost does freeze, don't try to fix it. Frozen heaps and tumblers can be easily damaged if you try to turn them. Wait for a full thaw and then attend to your compost.
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In Dry Areas, Add Water
Arid climates have cold winters that lack direct sources of moisture. If your compost pile isn't getting any rain and humidity levels are low, sprinkle water on the pile on days when the temperature rises.
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Save a Little Dry Material for Spring
As winter turns to spring, many piles encounter an overabundance of moisture and get a little slimy. So save some dry autumn leaves or straw to layer onto your pile as spring approaches.
Originally Published: October 30, 2017