Composting during colder months requires more caution. Unlike warmer seasons, winter composting struggles with slow decomposition, increased pest risks, and the potential for introducing harmful contaminants into your garden soil. The biggest mistake gardeners make is adding materials that won’t break down properly, leading to unusable compost and potential crop damage next year.
Why Winter Composting Is Different
Cold temperatures drastically reduce microbial activity, the engine of decomposition. Smaller piles can freeze solid, while even larger ones decompose at a snail’s pace. The core may stay warm enough to function, but turning the pile is impractical—you’ll lose valuable heat.
This slow breakdown creates two major problems:
- Pest Attraction: Undecayed food scraps linger longer, inviting rodents and insects.
- Pathogen Survival: Insufficient heat means weed seeds and plant diseases survive, potentially re-infecting your garden.
Additionally, finding enough “brown” materials (dried leaves, grass) can be tricky in winter, leading to an imbalanced “green” (food scraps) overload. This results in foul odors, nutrient loss, and further slows decomposition.
The Worst Winter Composting Mistake: Animal Waste
The single most harmful thing you can add to a winter compost pile is animal manure or contaminated bedding. While it seems like a readily available fertilizer source, winter’s low temperatures won’t kill the pathogens, parasites, and bacteria (like E. coli ) it contains. These contaminants remain active, posing risks to soil, plants, and human health.
High heat (130°F–160°F) is required to destroy insect eggs and harmful microbes. Without it, pests like green June beetles can thrive, causing years of garden trouble. Animal waste also attracts flies, beetles, and cockroaches—all of which multiply in cold, slow-breaking compost.
Beware of Treated Plant Materials
Free straw, hay, or grass clippings from farms or communities can be contaminated with persistent herbicides. Some pasture treatments pass through livestock unharmed but concentrate in their waste. These chemicals don’t break down in cold compost and can devastate sensitive plants like tomatoes, peppers, and beans.
- Common Culprits: Look out for clopyralid, aminopyralid, and picloram—herbicides that cause plant distortion, stunting, and even death.
Other Materials to Avoid
While animal waste and treated materials are the biggest dangers, other items slow decomposition and create issues:
- Large Pieces: Eggshells, citrus rinds, and paper break down faster when shredded.
- Excess Moisture: Leads to foul odors and poor texture.
- Imbalanced Ratios: Maintain a 1:4 green-to-brown ratio.
Conclusion
Winter composting can be productive if done carefully. Avoid animal waste, treated plant materials, and unbalanced piles. Stick to basic greens and browns, and wait for warmer temperatures before turning your compost. Protecting your compost now will ensure a healthy garden next year.
