Learn exactly how to compost in winter, even in freezing climates. This expert tutorial explains pile size, green materials, turning frequency, insulation strategies, and step-by-step results. Perfect for gardeners who want finished compost by spring.
How to Compost in Winter: A Complete, Practical Guide
Most gardeners think of composting as a warm-weather ritual, steaming summer piles, bursts of microbial activity, and beautifully crumbly compost ready for top-dressing beds. But composting does not have to stop when the temperature plunges. With the right approach, winter composting can be not only possible but highly productive, giving you finished compost just in time for spring planting.
This guide walks through how to compost in winter using real-world principles, actual temperature readings, and two fully documented winter piles. Whether you garden in Zone 6 or Zone 2, you will walk away knowing exactly how to keep a winter pile warm, active, and cooking through snow, frost, and freezing nights.
What Exactly Is Compost?
Compost is the final, stable product of fully decomposed organic matter. It is rich in:
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Beneficial microorganisms
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Essential nutrients
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Moisture-retentive organic particles
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Disease-suppressing microbial activity
It can be used to top-dress lawns, amend beds, improve soil structure, and increase fertility.
Composting, at its core, requires four ingredients:
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Greens (nitrogen): kitchen scraps, grass clippings, pumpkins, coffee grounds
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Browns (carbon): sawdust, cardboard, leaves, shredded paper
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Water: moisture fuels microbial activity
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Air: oxygen allows heat-generating bacteria to dominate
If you have all four, you can make hot compost, even in winter.
Why Is Winter Composting Harder?
Composting in winter presents two major challenges.
1. Cold temperatures steal heat from the pile
As outside temperatures fall, the center of your pile loses heat more quickly. Since heat is produced by microbial activity, this creates a negative feedback loop:
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Cold air → cools pile
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Cooler pile → microbes slow
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Slow microbes → less heat
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Less heat → cooler pile
Without intervention, your compost can stall completely or freeze solid.
2. Lack of green materials
During winter:
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No lawn mowing
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Minimal fresh yard waste
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Frozen gardens
This leaves you low on nitrogen-rich “fuel,” unless you store and collect winter greens aggressively.
The Four Principles of Successful Winter Composting
These are the four pillars that make winter composting not just possible but reliably effective.
1. Make Your Piles Bigger
In summer, a hot pile can be as small as 3 ft wide.
In winter, you need:
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4.5–6 ft diameter piles
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Taller piles with dense material
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Enough volume to retain internal heat
Bigger piles = better insulation.
The only limitation is your ability to reach and mix the center.
2. Use Alternative Green Materials (Aggressively)
Since grass clippings vanish in winter, you need substitutes. Here are the best winter alternatives for green material.
Kitchen Scraps (Stockpiled in Buckets)
Store scraps in:
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Five-gallon buckets
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Lidded bins
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Outdoor or unheated garage areas
Cold storage prevents decomposition and odor, keeping scraps stable all winter.
Pumpkins & Jack-O’-Lanterns
These are gold. They break down fast, generate heat, and are abundant from October to December. Tell neighbors to give you theirs. They fuel winter compost piles like nothing else.
Used Coffee Grounds (Starbucks is the best source)
Starbucks has a nationwide “grounds for gardeners” program. Coffee grounds:
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Add nitrogen
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Increase heat output
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Are available year-round
Drive-through Starbucks produce more grounds more quickly.
Manure (optional)
Great nitrogen source, but requires safety temperature requirements. Use only if you’re comfortable handling manure according to USDA guidelines.
Urine (yes, really)
Not glamorous, but a potent nitrogen booster if you’re short on greens.
The key is volume: winter composting succeeds only when you gather greens aggressively.
3. Recharge the Pile Every Time You Turn It
Each time you turn a winter pile, you must add greens—at least:
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5 gallons of kitchen scraps, or
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Equivalent coffee grounds
Why? Because turning releases heat. In warm seasons, turning alone revives the pile. In winter, you must “refuel” with nitrogen every time.
This keeps internal temperatures from dropping and maintains bacterial dominance.
4. Don’t Turn More Than Once per Week
Turning too frequently causes:
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Heat loss
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Exposure of warm materials to cold air
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Freeze-ups if you lack the greens to recharge
Ideal winter turning interval:
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Every 7-14 days
Turn only when:
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You have accumulated enough greens
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You are ready to recharge the pile
Winter composting rewards patience.
How to Know When Your Winter Pile Is Finished
A winter pile can be considered finished when:
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The temperature no longer rises after turning
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You have run out of browns (or nearly so)
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The texture becomes crumbly, dark, earthy, and uniform
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It smells like fresh soil
Sometimes, the outside freezes, but the center remains warm and active. That’s normal—just keep turning weekly and let it cure until spring.
Documented Results: Two Real Winter Piles
Below is a summarized walk-through of two actual winter piles built in Zone 6 (Pennsylvania). Temperatures, materials, and results prove that winter composting works—even through snowstorms and single-digit nights.
Winter Pile #1: Built November 21
Temperature outside: 42°F
Ingredients:
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25–30 pumpkins
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10 gallons of kitchen scraps
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Large bags of yard waste
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Sawdust (browns)
Key results:
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Heated quickly
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Pumpkins decomposed within one week
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Pile stayed active throughout late November
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By mid-December, pile was nearly finished
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Minimal turning required
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Cured all winter outdoors
This pile finished fast because:
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The material mix was ideal
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Temperatures were cool, not extreme
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Pumpkin volume was high
Winter Pile #2: Started January 3
Temperature outside: 28°F
This pile had fewer greens, making it a perfect example of a typical mid-winter challenge.
Materials:
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Coffee grounds
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10 gallons of kitchen scraps
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Sawdust + egg cartons
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Jack-o’-lanterns
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Water
Winter conditions:
Nights below 10°F, consistent snow, long freezing periods.
Key results:
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Internal temperatures reached 80–100°F
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Pile survived extreme cold without freezing solid
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Regular recharging kept it cooking
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Grew large enough for strong insulation
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By early March: fully active
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By early April: finished compost
This proves that even under harsh conditions, winter composting stays active when you follow the four principles.
Complete Step-by-Step Method for How to Compost in Winter
Here is the winter composting workflow:
1. Build a larger pile
4.5–6 ft wide. Mix as you go. Keep it moist.
2. Accumulate greens continuously
Buckets of kitchen scraps
Coffee grounds
Pumpkins
Anything nitrogen-rich
3. Turn only once per week
Add greens each time.
Mix quickly to limit heat loss.
4. Expect outer freeze, inner heat
Don’t panic when the outside crust freezes.
The center can stay 60-100°F.
5. Stop adding greens when browns disappear
Then cure the pile until spring.
6. Confirm finished compost
Dark
Crumbly
Smells like soil
No identifiable scraps
FAQs: How to Compost in Winter
1. Can compost piles stay active in freezing weather?
Yes. The outside may freeze, but the insulated center can stay above 60°F with proper size and green input.
2. Do I need a compost bin for winter?
No. Open piles work well. Bins can help insulation but are not mandatory.
3. Should I cover my winter compost pile?
Many experts leave piles uncovered. Covers reduce heat loss but can create mold hazards.
4. What is the best green material for winter composting?
Pumpkins and used coffee grounds are the most powerful winter greens.
5. Can I compost without turning in winter?
Yes, but the pile may freeze and stall. Turning and recharging are essential for hot compost in winter.
