Will Compost Still Break Down in Winter?

Compost needs to be warm, so as your garden is hit by freezing temperatures in winter, will the compost still break down? If your balcony compost bin is exposed to icy conditions, or your mini compost pile freezes over, there likely won’t be enough moisture and heat to keep things breaking down efficiently.

So if your area frequently sits below-freezing in winter, read on to find out what happens to your compost, and tips on how you can encourage it to keep going!

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Will a compost bin work at 32 degrees Fahrenheit?

If freezing temperatures hit, your compost will only continue to break down if you’re still regularly adding green organic matter.

As garden waste is less common in winter, especially in a smaller garden, the decomposition process in your compost bin will start to slow down and it may even become dormant.

This is especially true in smaller gardens where our compost bins are smaller in size. A large compost pile may be insulated enough to keep the heat in. But a small balcony composter will lose heat quickly.

So in US hardiness zones 7 and below, your compost will usually resume breaking down in the spring as temperatures rise.

Can I speed up the composting process?

There are a few ways to make sure your compost continues to break down throughout the winter. One way to speed things up is to regularly add nitrogen-rich organic elements. These will increase microbe activity in your compost pile which will keep things warmer.

These ingredients are great items to add to a compost bin, and they can even act as compost accelerators:

• Fresh coffee grounds
• Green garden waste like grass clippings and green stems
• Animal manure (horse, cow, goat, sheep, chicken)

If you’re not a coffee drinker, don’t own a farm… and don’t have much garden waste to add, you may be able to strike a deal with a local coffee shop, horse stables, or tree surgeon!

Hot composting

Another way to keep things actively breaking down in winter is to create a hot composting bin. One of the critical differences between a cold and hot composting bin is the amount of heat involved.

A cold composting bin will be active through the spring, summer, and autumn. But as winter hits, it will become dormant — unless you create hot composting conditions!

You can buy a hot composter, which has built-in insulation that keeps conditions at more optimum levels for microbes. Although a little on the pricey side, this hot composter from Amazon claims to produce compost in as little as 5-8 weeks. Or alternatively, you can attempt to create a DIY hot compost bin yourself.

Another option is a tumbler compost bin. This tumbler compost bin from Amazon allows you to easily aerate your compost and keep the decomposition process.

Why does compost need to be warm?

It’s the microbes and fungi inside your compost bin that are doing the hard work and breaking down organic matter. As they digest old kitchen waste, they create heat and also multiply. But to keep reproducing in winter, they need a warm ambient temperature or plenty of nitrogen-rich organic matter to feed on.

Too little heat, for example in freezing temperatures, activity will stop altogether. But too much heat and the microbes and fungi are unable to function. The best temperature for your compost bin is between 135º-160º Fahrenheit (57º-71ºC).

Alternative composting methods to use in winter

If the idea of regularly heading outside into the cold to add to your compost bin doesn’t sound appealing, there are other composting methods you can use.

These methods will ensure your kitchen waste, cut flowers, and coffee grounds can be turned into nutritious fertilizer indoors.

Bokashi composting

A Japanese composting method that uses fermentation to break down your kitchen waste. As you add organic elements, you sprinkle a layer of ‘bran’ that has been inoculated with beneficial composting microbes. It’s a great composting method to use in winter, as it can be kept indoors! This Bokashi compost bin kit from Amazon comes with a packet of Bokashi bran ready to use.

Bokashi compost bins are airtight and specially made to keep smells at bay. They will also usually feature a spigot tap for you to drain away any liquid. This liquid can then be diluted and used as plant feed which is great for house plants.

The organic waste quickly begins to ferment (not decompose). And after a few weeks, you’ll have a bin full of fermented organic waste which can be added as a fertilizer to other compost.

You can add it as mulch on potted fruit trees to provide nutrition in the spring. Or simply add it when repotting house plants, or when adding compost to any new planter.

Vermiculture composting

Another efficient composting method that can be used indoors in winter is vermicomposting. It’s a closed container that uses a unique species of worm to digest organic waste. As they process the organic matter, they turn it into nutritious worm-casting compost (basically worm poo!).

You can usually buy a vermiculture kit, which may come with worms. Or you can create your own DIY vermiculture container and buy and add worms separately. This US-made worm composter from Amazon comes with a handy accessory kit to help you set up and manage your vermicomposter with ease.

Only a certain species of worm can be used, so don’t dig up earthworms from outside, as they won’t survive in a bin filled with kitchen waste. They also need unique conditions to survive, so check out our guide to vermicomposting to make sure your vermicomposter is a success.

You could even have two composting methods on the go. With two Bokashi bins inside and a hot composting bin on your balcony. With multiple bins, you’ll always have a bin ready to add waste into if any fill up. Plus, you can combine the Bokashi fertilizer with crumbly compost from your hot compost bin.