How Can I Help My Worms Survive The Dangerous Winter Cold?

How Can I Help My Worms Survive the Dangerous Winter Cold?

The short days and long, cold nights of winter present a very real threat to your treasured worms. We worm farmers know the many benefits of a nutrient-dense heap of rich worm compost, and our nurturing of our red wiggler team through the growing season has resulted in a happy, healthy, productive unit.

Alas, the inhospitable temperatures of winter can wipe out your entire worm population with one hard freeze.

With some preparation and attention to detail, you can help your worms withstand the winter cold and remain productive through it all, as they continue to compost your table scraps. Fatal accidents can be avoided! Today’s blog post will empower you with the know-how you’ll need for winter worm composting success.

Regulate Temperatures in Your Worm Bin

The key to success with winter worm farming is understanding the red wigglers’ response to their microclimate (the environmental conditions inside of the worm bin). In the artificial environment you create in you bin, temperature is the main thing that determines the ultimate productivity of your worms. That’s why temperature regulation is the most important factor to keep in mind in the barren winter months.

The Best Temperatures for Composting Worms

When given a choice to set your home thermostat to balmy or brisk, there’s generally a sweet spot in the middle for each of us. The same applies to composting worms – they too seek mild to warm temperatures rather than those in the extreme.

Consider using a worm farming thermometer to help you accurately measure the bedding temperature inside your worm bin.

This guide will assist you as you monitor and adjust the conditions in your bin this winter, and all year long.

Between 55 and 77 ℉

This is the sweet spot for the temperature inside of your worm bin. Red wigglers not only survive, they thrive when conditions are between an ideal 55 and 77 degrees. Within this range, you can expect your worms to consume and cast off at least half of their body weight in food each day. Furthermore, worms will reproduce rapidly at this temperature, increasing both the population and productivity within your worm bin.

40 to 55℉

Within this temperature range, composting worms will exhibit sluggish eating, mating, and reconstituting of your kitchen scraps. This is a chilly environment for worms that prefers a warm and humid climate. In nature, red wigglers tend to burrow deeper into the earth for insulation. In most worm bins this is not an option. Your worms will likely survive but may attempt to escape the bin in search of more hospitable conditions.

32 to 40℉

Low temperatures render red wigglers nearly dormant, and relentless cold drastically decreases decomposition of organic matter resulting in a scarcity of easily consumable worm food.

Below 32℉

If the temperature within the bin plummets below 32 degrees, our beloved worms, being made of nearly 90 percent water, just can’t hack it. Temperatures below 32℉ are fatal, and will most likely kill off your entire composting community.

On the other side of things:
Temperatures that exceed 80 degrees are almost as dangerous as freezing temperatures. Red wigglers are not likely to survive above 85 degrees.

Shelter Your Red Wigglers from the Cold

Now that you know what can happen to your worms when things get too chilly, we will teach you how to keep them warm (and safe!) An effective cold weather shelter provides your worms respite from the elements, and allows a worm farmer easy access for regular maintenance. Without shelter it is almost certain your vermicompost production will halt and you will need to start from scratch when your dormant cocoons start to hatch in the spring.

This winter you may have to McGyver your situation and use any combination of resources to ensure your worms keep up their hot-n-heavy routine. The options below offer you a few ideas for creating a maximal level of protection using minimal time, effort, or materials.

Move the Bin Indoors

The absolute best thing you can do is to welcome your worms into your home for winter. Sharing your heated, insulated home is a very easy solution that requires only a bit of space for your worm bin. The red wigglers will gladly help eliminate table scraps and provide some free entertainment for the kids in exchange for their comfort through the jarring winter.

I know some of you may be a little squeamish about the idea of bringing worms into the house. Just remember that red wigglers will almost never attempt to leave a properly maintained worm bin. As long as you keep up your end of things, you will not have any issues come out of keeping your worms inside.

Relocate your worms to a shed or garage

If the house isn’t an option, moving the bin to a shed or garage may be the next best thing for worm farmers willing to make an extra effort to the maintenance of their winter vermicompost. A shed is a great place to get out of the wind. A garage is perfect for providing a dark and an inconspicuous location for a worm bin.

However, an uninsulated set of walls on a cement slab will still have an air temperature that falls below safe levels for our revered red wigglers. A heat source such as a seed starting mat, amphibian heat rock, or a geothermal setup can be crucial. If you choose to relocate your worms to a room with a cement foundation, elevate the bin off the ground to allow warmer air to circulate beneath to prevent frozen substrate.

Bury your worm bin underground

With a bit of planning, elbow grease, and creativity you can set up your worms with an underground bunker to withstand whatever winter throws their way. Left to their devices, the worms will reward your efforts with plenty of new worms ready to work when they are unearthed in the spring.

  1. Dig a hole slightly larger than your worms’ bin.
  2. Submerge the bin and insulate any gaps with dry leaves, straw, Styrofoam, or other material that won’t become waterlogged.
  3. Layer straw over the top for more insulation and ease of removal for access to the worms.
  4. Provide a nitrogen rich meal that can sustain the worms for the duration of the cold.
  5. Avoid opening the lid. Though it is tempting, it will allow precious warm air to escape and lower the overall temperature of the enclosure.

A last resort

Some of our more risk-taking vermicomposters may choose to take their chances by allowing their worms to remain outside during the long winter months. Those attempting this method will find that the larger the bed, the more success they have. This is due to the internal heat a large bed generates and retains from microbial decomposition.

Worms will gather near this heat to escape the cold or even frozen edges. Covering the bed with heavy clear plastic will mimic a greenhouse, offer moisture protection, and contain any residual heat. Unfortunately, this approach often results in a massive die-off of the red wigglers. If your options are few, why not try?

At least if everything falls apart, your worm cocoons will still be there, ready to hatch, when things warm up again in the spring!

Feed Your Worms And Put Them to Bed

Another important step to ensure the winter survival of your composting worms is to make sure to provide adequate food and quality bedding. You can expect to feed cold over-wintered worms less food less frequently than you have been used to. However, if your worms will stay with you in the home you can expect them to maintain a more regular appetite. Provide a high quality bedding to supply moisture, a food source, and a dark place to keep busy. The worms’ bedding will last much longer in very cold conditions, potentially through the entire winter.

Keep in mind that bedding must remain damp to provide adequate moisture for your worms. Worms breathe through their wet skin. Too much water in the bedding fills in the tiny air pockets they rely on for oxygen beneath the surface. Conversely, too little water leaves worms dry and starved for oxygen.

Now What? Some Final Tips and Hints

The measure of success in winter worm composting will be different for everyone. Will your resolution this year be to try a new method of insulating your red wigglers? Maybe just having that population of worms survive would be great. If you follow our suggestions you will create a winter haven for your red wigglers so they will stay happy in their home, a valuable source of nutrient rich compost come spring!

Now that you have your red wiggler survival guide for the winter, it’s time for you to take action and protect them from the cold. The first step is to get yourself a worm farming thermometer so that you can always stay on top of the temperatures in your worm bin. Next, go ahead and choose the method you will use to protect your worms from the cold.

Once you finish getting your worms set up, there is only one thing left that you may want to do. Sign up for The Squirm Firm’s newsletter! We will send you just one email per month, providing free tips, tricks, and how-tos that will help you on your journey to becoming an expert worm farmer. Just type your email address into the bar at the top of your screen. It’s that easy! See ya next time!

Readers Comments (6)

  1. Lawrence Lievense January 2, 2017 @ 6:22 pm

    Why is there no mention of how to heat wormbins with actual heaters? Like acquarium heaters or lizard heaters or soil cable heaters?

    • Hi, Lawrence-
      Thank you for keeping us on our toes! Using a heating element such as an aquarium heater, lizard heater, or soil cable heater is a great way to maintain a safe temperature range within your worm bin.
      This method is addressed in the article, but is worth repeating. “A heat source such as a seed starting mat, amphibian heat rock, or a geothermal setup can be crucial.”

      Have you tried any of these methods? What are you using this winter? Let us know what has worked for you!

  2. Thanks for that. One question from me, I am in S. Oregon, a pretty mild zone, 8a. I tend my worms outside location with a great deal of organic matter over them. I notice the worms do go deeper, but are still accessible. On nights near or just under freezing I had a few books of straw. Am I on track, or no? Thanks.

    • Hi Jim, thanks for checking in. If your worms are doing just fine as they are, the addition of straw can only benefit them further. It provides insulation, organic matter for breakdown and the heat that results, and it will help to keep their pile aerated and well-draining. It sounds like you are doing great! Keep it up!

    • Hi, Renee. The short answer is that it depends. If you are just starting out and can plan accordingly- an outdoor worm bed built into the ground would be a viable option. Or if you could build a kind of box to put them in in the winter, and even heat it, then insulate them in. Actually, there are lots of creative ways that worm farmers in cooler regions have been really successful! I say, give it a try! We’re here to help you along the way! Check out , There you’ll find 5 steps to preparing your worm bins for winter!

  3. I was wondering what kind of ‘winter’ you are talking about. In Halifax, NS it falls to -20C quite regularly at night. It’s often around -5 or colder daytime temperatures. Would it be possible to keep worms outside in these temperatures? I would consider a seed starting mat.


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