close up of plant with frost on the leaves

Will my composting worms freeze in the winter?

frozen scenery

When winter falls and the mercury drops, do the worms in your garden survive? The answer is: it depends.

If you live in USDA Hardiness Zones 7 and below, your worms may have a tougher time surviving the winters. (You can check what hardiness zone you're in here.)

Earthworms cannot live in freezing temperatures, and they will perish in the extreme cold. However, if you’re worried about your garden’s health or the health of the residents of your worm bin, you can relax. There are some options.

Read on below to learn the ins and outs of caring for a composting worm population in winter. 

Earthworms can’t survive freezing temps, but…their eggs can!

If you live in the coldest of climates, places where it freezes for many weeks at a time, the earthworms in your garden and compost pile are likely going to perish. Some worms burrow into the ground, surround themselves in slime and hibernate throughout the winter. However, if the temps get below freezing for long enough, you can say goodbye to your lovely wiggly friends!

However, earthworms lay eggs that are encased in small cocoons which protect them from the weather. When the weather warms up, little baby earthworms emerge from these eggs and repopulate your garden. 

There has been research proving that earthworms can be frozen and slowly thawed and returned to life, but it’s safe to say that trying this out in your home will lead to a messy result. We don’t recommend it! You can revive earthworms to some extent, but only if they have become dehydrated. As of right now, there is no known way to revive frozen earthworms at home.

How to protect earthworms from the cold

compost heap

The best way to protect your earthworms is to bring them indoors, if possible. Obviously, this won’t be possible if they are in your outdoor garden or compost heap. Another possible solution might be to mulch your garden beds thickly to try and insulate them from the cold. This works to some extent for plants, so there’s a chance it may help your worms too.

Apart from that, there really isn’t a whole lot that you can do for your earthworms in the winter. Just let nature run its course, and in due time, provide plenty of food so the freshly hatched worms can feed and grow. If you’re interested in reading about worm eggs and how long they take to hatch (in case you left your worm bin outdoors and found yourself left with just eggs, for instance), you can find more info here.

We live in Zone 7a and I can say from experience, our winters are mild enough that our outdoor worm bin has withstood freezing temps and even a few days with snow on the ground. I like to add insulating material like extra bedding or straw to the bin and that has helped my outdoor bins from freezing and killing our clew entirely. Again though, we live in 7a which has relatively mild winters. If you're in Zones 7-10, you likely have little to worry about in terms of an outdoor bin freezing in the winter.

Keep your worm bin nice and warm indoors

If you live in the coldest Zone 1-6 and plan on keeping your worm bin outside, it may be something you’ll need to rethink, because in the winter your squiggly composters likely die. Many people who use a worm bin keep it indoors for the sake of convenience, and because it isn’t messy or smelly, there are usually no obvious downsides unless you just don’t like the sight of composting worms.

We would recommend keeping the bin somewhere out of sight indoors, in that case – tucked away in a corner, where prying eyes won’t see it and you won’t be bothered. Don't confuse indoors with above freezing either though! Some people have made the mistake of putting their worm farm inside an unheated garage - it might be safe from snowfall, but worms don't do very well under 50 degrees Fahrenheit. If you're keeping it in a garage, make sure to keep an eye on the garage temperature.

Worm Bucket worm bin

If you don't have a worm bin but would like to start and you happen to live in Zones 1-6 then it might be a good idea to switch to something like our Worm Bucket, which is an easy to use, transportable worm bin that you can keep anywhere inside your home. 

We designed the Worm Bucket to be small enough to keep in an apartment or condo where space is a concern, but also to be big enough to give you a relatively decent harvest. When Audrey harvested the Worm Bucket on our Youtube channel, we got about 4.5 pounds of harvested worm castings in just a couple months. Watch the video below to see the harvest: