Composting is, in part, a temperature-dependent process. But that doesn't mean that you have to stop composting in winter. How you keep your compost going depends on what sort of composting you do.
To compost in winter:
- Hot composters carry on. Hot composting is an intensive process. Hot composters collect their composting materials in piles until they have enough stored to build a compost heap all at once. They carefully layer their green and brown materials into the heap, ensuring that the right mix of materials is used and that there's plenty of air built into the heap. Once the heap is built, microbial activity causes the compost to heat up - and that will still happen in winter. Adding some insulation to your compost bin will help to keep the heat in and your hot heap composting rapidly.
- Cold composters continue. Cold composting is a much more laid back affair. You add your materials to the compost bin as and when you have them. In the average household, the mix of garden waste and kitchen waste, plus some waste paper and cardboard, means that the mix of materials in the heap is right. Scrunched up paper or cardboard tubes, plus any twiggy bits, make sure there's enough air in the heap. It won't heat up though, and the compost takes longer to rot down - especially in winter. For the best results, site your compost bin where it will catch any winter sun. Even so, a bin that was full at the beginning of winter should have finished composting by spring.
- Worm composters take shelter. Worms, like many of us, slow down in cold weather - so you need to make sure that you're not adding more kitchen waste to your worm compost bin than they can cope with. And if they're left outdoors then they're at risk from drowning if there's a lot of rain or freezing when the temperature drops. If you can bring your worm bin indoors (a garage or shed is ideal) then that's great - otherwise try insulating the bin and giving it a hat to keep the worst of the rain off. But don't obstruct all the air holes, or you'll suffocate your worms!
- Trench composters dig deep. Trench composting prepares very nutritious soil for hungry crops next year. It's easy enough to do - dig a trench to about a spade's depth where you will be planting your peas and beans, or squashes and melons, next year. Put the soil to one side. Add kitchen waste to the trench as and when you have it, and cover it with soil. Once the trench is full, cap it off with the rest of the soil and leave it to settle. By the spring you'll have rich planting holes that give your crops a real advantage. But you'll have to be quick and dig those trenches before the soil freezes solid!
- Bokashi composters stay indoors. In some parts of the world the winter weather is so severe that outdoor composting really isn't an option - you won't be able to get to the bin. In that case, try investing in a pair of buckets with lids and taps, and a supply of Bokashi (EM) bran. Then you can store your kitchen waste in the buckets all winter, and it won't smell bad or go off, and you can add it to the outside compost heap whenever you are able.
Wherever you are, and however you compost, there's a way you can continue through the winter and avoid wasting all those compostable materials. Always remember the main points of composting - get the mix of materials right, keep the heap moist, and make sure there's air in there - and your compost heap will be happy right through the winter. And don't forget that fall is the time to collect fallen leaves for making leaf mold compost!