Getting your compost worms ready for winter

Estimated reading time: 6 minutes



It’s about that time of year that many of you are getting your compost worms ready for winter. For some of us, it means simply 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 indoor or outdoors this winter.

Red worms preferred environment

One of the great things about red worms, or red wigglers, is that they can 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 they are to 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 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 just like humans. They start to cozy up, burrow, and slow down. Much like us, after the worm too needs a little rest and relaxation. This is the natural flow of nature and should not be seen as a bad thing.

You’ll want to pay attention this time of year to how much your worms are eating. 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 especially true in small bins where worms can not travel away from the hot spot.

Worms indoors

When we are discussing indoors, we mean worm bins that are kept in a heated area. We will talk more about unheated sheds and truely outdoor worm bins in just 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 get your compost worms ready for winter. For reasons stated above, you want to avoid your indoor bin from going anerobic.

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 specific 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 some additional work to get your outdoor compost worms ready 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 aroud your outdoor bins for insulation

You are going to want to add loose stray or bales of hay around a truly 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 in 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
Additional food in the winter can help increase the temperature in the bin.

Over and over again on this website I will tell you to never 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 very sure you do not launch the temperature above 84 degrees and cooking your worms alive.


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Use an 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 nursery heating pads are water-resistant which makes 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.

Summary

It isn’t hard to get your compost worms ready for winter. Thankfully they tolerate winter well. With the right accommodations you can help your wiggily buddies get through the harshest winters.

If you have any questions, or suggestions on wintering your worm bin, leave them in the comments below!

Happy composting!

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