Getting your compost worms ready for winter

Estimated reading time: 6 minutes

It’s about that time of year when many of you are preparing your compost worms for winter. For some of us, it simply means some cold and rainy weather. For others, it can mean ice and snow. If this is your first year of vermicomposting, you may not know what to expect.

Today’s article breaks down what you should do if you plan to keep your worms indoors or outdoors this winter.

Red worms preferred the environment

One of the great things about red worms, or red wigglers, is that they can have a wide variety of temperatures. However, their preferred temperature is somewhere between 55-77 degrees Fahrenheit. Thankfully they are more sensitive to higher temperatures than lower temperatures.

In the optimal temperature range, worms eat quickly, make cocoons, and baby worms hatch. When you go under 50 degrees, worm activity slows down. You will notice they take longer to eat the same amount of food, and the population is not growing like in the late spring and summer months.

Feeding red worms during the winter

compost worms winter will eat less in colder months
It is common for worms to eat less during the winter/ colder months

As stated earlier, you will notice a decrease in productivity in your worms during the winter. As your red worms ready themselves for winter, they act like humans. They start to cozy up, burrow, and slow down. Much like us, after the worm, too, needs a little rest. This natural flow of nature should not be seen as a bad thing.

You’ll want to pay attention to how much your worms are eating this time of year. Worms will die in oversaturated or anaerobic environments above 84 degrees Fahrenheit. Many indoor vermicomposters do not adjust for winter conditions in their bin and accidentally cook their worms. This is especially true in small containers where worms can not travel away from the hot spot.

Worms indoors

When discussing indoors, we mean worm bins kept in a heated area. We will talk more about unheated sheds and truly outdoor worm bins in a moment. If you have your worm bin in a closet or spare room, you will likely only need to adjust your feeding schedule to prepare your compost worms for winter. For the reasons stated above, you want to prevent your indoor bin from going anaerobic.

You want to avoid feeding your worms more than they can eat within a week. When you taper, your feeding depends on your specific conditions, so we cannot give a particular recommendation. We suggest pocket feeding and observing how long it takes for the food to disappear.

Getting outdoor red worms ready for winter

You will need to do additional work to prepare your outdoor compost worms for winter. You don’t want to let your worm bin freeze. That will kill all of your worms. There are a few common strategies to help support your red wiggler buddies.

Insulate your container

compost worms winter can be aided by insulating with hay bails
Place hay or stray bales around your outdoor bins for insulation.

You will want to add loose stray or bales of hay around an exposed worm bin. This means lining all sides with a nice thick layer of insulation to help keep the heat in. Remember, a worm bin can also generate heat from decomposition. In nature, worms dig further into the earth to find the warm ground. A layer of straw, hay, or other insulating material will help act as a buffer from the cold.

Add extra food

Adding extra food scraps can increase bin temperature in compost worms winter
Other food in the winter can help increase the temperature in the bin.

Over and over again on this website, I will tell you never to overfeed your worms. However, this is the one instance you may want to overfeed your worms. Overfeeding will cause the temperature in your bin to rise. Some outdoor worm composters in extreme environments (i.e., Canada) intentionally let their bins go anaerobic.

A note of caution: If you use this strategy, be sure to have a way to measure the temperature of the bedding inside the bin. You will want to be sure you do not launch the temperature above 84 degrees and cook your worms alive.

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Use a plant heat mat.

If you have your worms in a shed and fear that they will freeze, you can use a heating pad for seedlings. These water-resistant nursery heating pads make them a safe option for keeping your worms warm. Place the tray underneath your bin or on the surface of your protective layer of bedding. There is no need to bury or place the heating pad directly on the bedding. As before, monitor that the heating pad does not increase the internal bedding temperature above 84 degrees.


It isn’t hard to get your compost worms ready for winter. Thankfully they tolerate winter well. With a little extra attention, your wiggly buddies will get through the harshest winters with suitable accommodations. If you have any questions or suggestions on wintering your worm bin, leave them in the comments below!

Happy composting!

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