The gardening season is over, except for houseplants and microgreens, and you’ve got a bunch of leftover compost. How can you store it? Can you keep composting during the winter? And can you compost indoors?
In the winter, you can store finished compost in its original compost bin or plastic bag, on a covered tarp, or in a plastic bin or garbage can with air holes. You can leave it outside in a place sheltered from rain and snow, or inside in a dry and temperate place. If the compost is alive with beneficial microbes or requires finishing, keep the compost moist.
Can You Compost In The Winter?
Just because it’s winter, doesn’t mean you can’t compost anymore — the process just slows down as temperatures drop. In hot composting, the inside of the compost will heat from bacteria, fungi, and insects breaking down organic matter into finished compost. Only when the compost freezes does decomposition stop, and in a big bin, it’ll take some frigid temperatures to freeze the centre. It’ll start decomposing again as soon as the temperature rises.
Why Store Compost In The Winter?
Reasons you’d want to store your compost include:
- Freeing up space in your compost bin. You may not need that extra compost right now, but you still have kitchen scraps to compost. This is especially true before winter, as you’ll continue to have the same amount of kitchen scraps, but the pile will decompose slower and you won’t have anywhere to put the finished compost.
- Protecting compost’s nutrients and beneficial microbes. Storing finished or nearly finished compost will protect it from rain and cold, which can leach away nutrients or affect the beneficial microbes inside. Properly stored, it’ll be protected, and given enough warmth and moisture, the beneficial microbes will continue to finish compost that’s close to being finished.
- Keeping extra compost handy for when you need it. The best way to store finished compost overwinter is by mulching your garden beds with it, but if you’ve already topped up your beds and have some left over, then you’ll want to keep it in reserve come spring for that time before your winter compost is ready. Or you’re saving the leftover compost that you bought.
How to Store Compost In The Winter
Mulch garden beds with compost
You don’t need to wait until spring to apply compost to your garden beds. Fall is actually an ideal time to add compost. By applying compost in the fall, the compost will continue to break down to feed the soil until the ground freezes, then pick up again as soon as the ground thaws. The nutrients will be available as soon as you sow or transplant. A thick layer of compost will also curb early weed germination.
Store compost in a container or between two tarps
The key to compost storage (with live beneficial microbes) is providing protection from the elements (like rain) and continued aeration. This sounds a lot more lofty than it is. Storage could be as simple as keeping it in your regular compost bin (if you don’t need the room for making more compost), storing it in a plastic bin or garbage can (with air holes!), or even just laying it on top of a tarp and covering it with another tarp.
If you bought your compost in a plastic bag, then just keep it in the bag it came in. Most bagged compost has been sterilized anyway, destroying any beneficial microbes but also ensuring that the compost doesn’t spread disease, fungus, and mould to your garden beds. Compost bags already come with air holes.
Place it outside or move it inside to a dry, mild location
You don’t even need to bring finished compost inside as long as you can keep most rain or snow off. You can achieve this by either building a shelter over your compost or just covering your bin with a tarp. The bigger the pile, the better to preserve the beneficial microbes and keep the compost going.
But if you don’t have the room outside, then bring the containers inside to a place that is dry and has a mild temperature. If you wish to slow down decomposition, store it in a cooler area. If you wish to speed it up, store it in a warmer location.
Keep it out of reach of children and pets, and somewhere that it’s stable. You don’t want to end up with compost toppling all over the floor, or even hitting someone as it tumbles down.
Keep living compost moist to keep beneficial microbes alive
While too much water can stagnate compost piles, beneficial microbes need moisture to survive. Keeping the compost moist will help them, especially if your compost still needs to finish.
If you’re storing store-bought, sterilized compost, then keep it dry.
How to Compost In Cold Weather
Composting in cold weather uses the same principles as composting in warm, but with a few twists:
Make room by harvesting finished compost in the fall
In the fall, remove finished compost to make room for winter composting. As compost will take longer to finish during the winter, you will find your composter fuller than ever as you continue to add to it. Fall is also a great time to top up your garden beds or your lawn with a fresh layer of finished compost. It too will take a break from decomposition during below freezing temperatures but pick up during the spring thaw, in time to benefit your awakening plants.
Gather dead leaves for overwinter carbon material
Hot composting works best when you layer green (nitrogen) and brown (carbon) materials, but in the winter, you don’t have as ready access to browns. Bag up fallen leaves, store them in a shed, and whenever you add kitchen scraps, add a layer of leaves.
Avoid putting wood ashes into the compost, as too much wood ash will raise the pH and slow down decomposition.
Continue to layer green and brown materials (and cut them to size)
To keep your compost pile warm, it’s important to layer green and brown materials. These layers will increase the heat as the nitrogen sources break down. To further speed up your compost pile and keep it from filling up too fast, cut materials into smaller pieces. Many composters find cutting up kitchen scraps to be a meditative and enjoyable part of their day.
Avoid turning the pile
Yes, turning the pile is essential for aiding decomposition, but in the winter, this can slow down decomposition as you expose the inner compost to cold air. It’s better to wait until spring arrives. Besides that, it’s just difficult to turn a half-frozen pile in knee-deep snow, so save yourself the effort.
Insulate and cover the pile
Another method to keep compost bins warmer is to surround them with insulating materials like bags of leaves, straw bales, or wood chips. A layer of insulation will help the compost stay that much warmer.
Just like in warm weather, too much winter rain or snowmelt can cause anaerobic conditions to develop. The compost will reek. Hot composting requires oxygen. So either keep your compost bin in a sheltered place or cover it with a tarp.
Can You Compost Indoors?
Yes, you can compost indoors, whether in the summer or in winter. While technically you could do hot composting indoors if you have enough room, there are two composting methods better suited to small abodes: vermicompost and bokashi.
The benefits of both include that they take up little space, don’t smell, and you don’t have to trudge your way through the snow to deliver the food scraps to the compost pile. Neither is superior to the other, as they both have distinct advantages and can even work in conjunction. Pick the method that fits your life best.
What Is vermicompost?
While hot composting makes use of earthworms, vermicompost is all about red wiggler worms. A vermicompost bin usually involves multiple layers with paper scrap beds with grit for the worms to live in while they digest fresh kitchen scraps into nutrient and beneficial microbe rich worm castings. Many people who use worm castings in the garden swear by them. The bins are easy to DIY or you can buy more sophisticated complete systems.
Don’t worry about escapee worms, as worms will only try to escape the vermicompost bin if there’s not any food inside. To avoid problems with fruit flies, freeze scraps for 24 hours and let thaw before burying them in the vermicompost pile.
You won’t need to worry about the proportion of carbon sources to nitrogen, although worms need carbon like shredded paper. They also need something for grit, either fresh soil or even coffee grounds, in order to digest. You can feed them everything you would a compost bin, except for citrus.
What Is bokashi?
Bokashi isn’t actually a composting process. It’s a fermentation process. Using an airtight bin to create anaerobic conditions, you sprinkle layers of bokashi bran in between food scraps, then seal it to ferment for 2 weeks. After the fermentation process, you finish it by burying it underground or in a soil factory (a bin filled with living soil that has air holes). Under the soil, beneficial microbes (and insects, if burying it underground) decompose the fermented scraps in as little as 2 weeks.
During the fermentation process, you will also drain excess moisture, which you can use as a fertilizer (compost tea) or as a drain cleaner.
Bokashi doesn’t use carbon sources at all — in fact, it can only break down food scraps. But while you can’t compost paper napkins or paper tea bags in this method, you can add meat, fish, and fat.
Bokashi requires more investment to get started (with special airtight bins costing around $50 – $70 each), but once you get the bins, bran is only $20 per bag, which will last you a while.
If you prefer to bury the fermented scraps outside, then you can store them in a plastic bin until spring.
Will my compost attract animals over the winter?
Adding new food scraps won’t attract new animals during below freezing weather, as the food scraps will freeze before creating any odour. However, it’s still a good idea to bury them.
Compost bins and piles will attract animals like mice (or even insects like bumble bees or wasps) looking for a pleasant place to rest and survive the winter. Nesting, either by mice or wasps, is usually a sign that your compost is too dry. It should be as damp as a wrung out sponge.
If you have mice nesting in your compost pile, take advantage of warm snaps to moisten the pile and turn it. The compost pile will hopefully heat beyond what’s comfortable for the mice, but even if it doesn’t, mice don’t like wet conditions or disturbances. A compost tumbler, which is raised above the ground, will keep mice out.
You may also want to use indoor composting methods like vermicompost or bokashi for kitchen scraps during the winter, then start outdoor composting again in the spring.
Should I add worms to my winter compost?
No, you don’t need to add worms to your winter compost. If your compost is on the bare ground, then earthworms will find their own way to your compost bin during the warmer months. When air temperatures reach below 54F (12C), then they’ll slow down. Below freezing, they’ll die.
While you don’t need to add worms to a compost, they can be beneficial. Don’t add worms to tumbler composts. Worms don’t like tumbler composts as they heat too much and they rotate.
Can compost worms survive winter?
Worms that burrow deep into the soil (like nightcrawlers) can survive the winter, but worms who remain near the surface (like red wigglers) can’t. Night crawlers don’t even hibernate — they just burrow below the frost line, then emerge whenever the weather warms. Because red wigglers remain above the frost line, they’re killed by freezing temperatures. But don’t worry. They will have laid eggs protected by small cocoons that can survive the winter and hatch come spring. Worms have evolved to survive the winter in one way or another.
What plants should I avoid in my compost during the winter?
You should avoid adding the same plants to your compost pile during the winter as you would the summer. These include toxic plants, diseased plants, pesticide-treated plants, and black walnuts. Also, avoid putting wood ash from fires in your compost bins, as the wood ash will raise your pH and slow decomposition.
Do I need to keep track of my compost temperature?
You don’t need a thermometer or keep track of compost temperature for hot composting, but it definitely helps and speeds up the process. Many home composts that start out using the hot composting method actually end up cold composting instead, simply because the gardener doesn’t get their pile hot enough. Cold composting takes longer (a year) and can develop smells. If you take the temperature (from several spots), then you’ll know when to turn the pile and add more material, and when to leave it alone to do its thing. Instead of months, creating finished compost will only take weeks.
Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden centre helping people buy plants, gardening products, and lawn care products. He has real estate experience and he is a home owner. Jamie loves backyard projects, refinishing furniture, and enjoys sharing his knowledge online.