Don't stop composting just because it's cold outside. While the decomposition process slows down, your compost pile will keep working all winter long. Just follow the tips in this factsheet. Next spring you'll be glad you made the effort.

Fall preparation
To prepare for winter, empty out as much material as possible from your composter. Dig unfinished compost into garden beds under a layer of soil. Finished compost can be stored in a dry place for use during spring planting. You should also return about 1/5 of your finished compost to your bin, mixing it with new organic materials, to help speed up the decomposition process when spring arrives.

Restart your bin by placing a 10 to 15-centimetre (4 to 6-inch) layer of plant stalks or brush at the bottom. Add a layer, up to 15 cm (6 in), of leaves (browns) and then an equal amount of food waste (greens). Top with 2.5 cm (1 in) of soil or finished compost. Repeat by layering browns, then greens, then soil. Always bury greens, especially food waste, in the top centre of the pile under a layer of soil, compost or leaves.

Over the winter months you will be generating more food waste than yard waste. In order to maintain a proper brown:green (carbon:nitrogen) balance, you will need a constant source of carbon to mix with the food waste. Fall leaves are an ideal choice.

Collect fall leaves for use in your composter during the winter. If possible, shred the leaves using a lawnmower or trimmer. Smaller pieces decompose faster and take up less space. Store your leaves in a closed garbage can or similar container. Note: Leaves stored in bags can become a nesting site for rodents. And, if leaves are left outside, make sure they are protected from wind, rain and snow.

Maintaining a hot pile
Keep layering the materials in your bin throughout the winter, alternating equal amounts of greens and browns, then a 2.5-cm (1-in) layer of soil. This will ensure that you're creating a "hot pile" which will keep the decomposition process going. While the helpful decomposer bacteria in your pile continue to work in temperatures as low as -15 degrees C, you can create additional heat by insulating your bin.

Don't worry if the outer edges of your pile are freezing. The decomposition process is still working in the centre of your pile and the freezing process will actually help break down organics, allowing the material to decompose more rapidly when the warm spring weather arrives.

Turning the pile
Turning the pile in winter may release too much heat. For this reason, it's important that you alternate layers of materials and maintain the necessary ratio of browns (carbon) and greens (nitrogen). If the pile is too wet once the warmer weather arrives, you should turn the pile once or twice and blend in more leaves or other carbon sources, or a small amount of soil or finished compost that you've saved from the fall. (See our Materials to Compost factsheet.)

Storing food waste
If you would like to cut your trips to the composter back to once every few weeks, store your food waste indoors in a container and cover it with coffee grounds, soil, coconut husk fibre (Cocofibre), or preservative- and paint-free sawdust. Or consider moving your composter closer to the house if you don't want to walk through the snow.

Winter alternatives
Composting with worms is a great winter alternative, either indoors, or outdoors using an insulated bin. All you need is a bin, red worms and bedding.