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How Do Worms Survive Winter?

Date Updated: Nov 22, 2022

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Worms in freezing temperatures

Composting worms aid in the breakdown of food scraps, but some of you may wonder how these helpful creatures can survive the harsh winter. Any vermicomposting bin set up in a northern state is likely to freeze. Will all the worms die? Should you attempt to save them? Will there still be worm castings for fertilizer in the spring if the worms die? Should you bring them inside?

Uncle Jim will address all of these questions and more in this blog so you may properly care for your worm farm in winter and have these wriggly creatures ready for the next season. 

Worm Resilience

Worms are not as delicate as we might think. In reality, they are one of the oldest species alive today. They have a relatively short reproductive cycle, and their eggs can survive in extreme conditions for up to a year. 

Worms in a worm bin are essentially domesticated, but their behavior remains instinctive. You might have 500 worms in a composting bin made from a tote, or a worm farm with millions of composting worms. Either way, you manage their surroundings and take responsibility for their well-being. 

How cold is too cold for a worm bin?

The first question you should ask is “what temperatures do earthworms prefer?” Here is a breakdown of the temperature ranges your worm population can endure: 

Too warm: Above 80°F

Ideal: 55 – 80 °F 

Tolerable: 32 – 54 °F

Too cold:  Below 32 °F

Keep in mind that these refer to the worm bin’s interior temperature, not the air temperature. We advise using a worm composting thermometer or an urban worm soil thermometer for the most accurate information.

The Reality of Worm Composting in Winter and What You Can Do

Vermicomposting in winter

Leave them as-is outdoors

This option requires the least work, but it also means that the majority of your worms will not survive the freezing temperatures. What will likely happen is they will lay eggs and let the next generation repopulate the worm bin. 

The eggs are viable for up to one year. If the adult worms lay eggs in the fall, the eggs can wait until the weather warms up in the spring. If worms do not appear several weeks into the warm weather, you might have to order more red wigglers from Uncle Jim’s Worm Farm

Insulate the outdoor bin

Insulating the worm bin

Worms require heat in order to produce worm castings. The composting process itself generates heat; but when the weather cools, the process will slow down. You can help retain the heat by adding insulation to your outdoor composters.

Worm beds in winter provide some insulation, but you can place hay bales outside the bin or attach insulation foam boards. 

Here are materials you can use to keep the worm bin warm and well-insulated:

  • Hay bales
  • Straw
  • Scrap carpet
  • Styrofoam
  • Bubble wrap
  • Insulating foam
  • Blankets

Be sure to leave gaps in the insulation for air holes and proper drainage of any excess moisture. 

Partially bury the outdoor bin

Buried worm bin

(Source: Pinterest)

The soil acts as an excellent insulator, sheltering your worms from extreme temperatures. All you have to do is dig a one-foot-deep hole and place the entire bin inside the hole. You can even add an extra layer of insulation for good measure. When the temperature drops, the worms will migrate to the bin’s bottom.

When winter is over, you can pull the worm bin out of the hole and return it to where it belongs. The only major problem is that you will not have easy access to the worm bin. It will be more work if you need to do any bin maintenance or harvest the castings.

Move the bin to a warmer place

If you do not want to completely move the bin into your house, there are other warmer options to choose from. Worms might be able to survive on your porch, in the garage, or in your garden shed. While not as warm as the inside of your home, these areas are still warmer than your yard.

If you only have a worm compost pile, we suggest moving them into a bin (like the Worm Factory 360) so they can be more easily managed. 

Check to see if you have a waste heat source, such as a dryer vent or a central heating exhaust vent. If you move the bin nearby, your worms may be subjected to hot bursts on a pretty regular basis.

Creating heat using a heating mat or lamp is also an option if the space still is not warm enough. Be cautious as this could be a fire hazard; make sure to keep electrical cords away from combustibles and moisture. 

Compost Indoors

composting indoors

If you do not produce a lot of organic waste, an indoor worm bin would be perfect for you during the winter months. Composting indoors is great because you can better control the environment in which your worms live. You can put them under the kitchen sink, in your laundry area, and even have them out on display if you have one of those tray-based bins. 

Contrary to what most people expect, worm bins do not stink or give off foul odors when done right. That only happens when you do not manage it properly. Make sure to only feed the worms kitchen scraps they can consume and you should not have any problems. 

And that is it! You should be properly prepared for vermicomposting in the winter. As you probably know now, it is not hard or impossible. All you need is a little bit of time to prepare and the right attitude. 

If you have any more questions about what worms prefer or are looking for any worm farming supplies, do not hesitate to reach out to our team

Frequently Asked Questions

Do worms hibernate in the winter?

Yes, they do. Regular worms can tunnel six feet into the ground before the soil freezes. They bundle up into a slime-coated ball, hibernate (a process known as estivation), and wait until the weather warms to wake up.

What do you do with worm casting in the winter?

Harvesting your black gold in the winter is still possible if you keep the core temperature of your worm bins in the ideal range. Combine this with a regular feeding schedule and bin upkeep, and you should be fine. 

The only thing that would be more difficult is sorting through the bin and harvesting the castings in the cold weather.  To make things easier, we recommend utilizing a tray based composter.

Are there better types of food to feed your worms in colder temperatures?

During the winter, worms do not have any particular diet. It does not matter what you feed them—normal fruit and vegetable scraps, coffee grounds, etc.—the only distinction is how much food you give to keep the worms alive. 

Worms eat less organic material during colder seasons than they would in the summer or spring because the cooler weather makes them more sluggish and slow-moving, not expending that much energy. 

8 comments on “How Do Worms Survive Winter?

  • Hey all,
    It’s starting to get cold where I live and I want to being my worm bin inside, but when I do i notice some worms start crawling up the sides (not a mass exodus, just 5-10). The people I live with are skeptical about having the bin inside, and escaping worms would be a dealbreaker. Does anyone know why they are exploring and how to prevent that? Otherwise I’ll have to keep the bin outside and they might not survive the winter.

    Reply
  • Dallas Hays says:

    those who claim these worms will dig deep enough in the winter to keep from freezing forget we are talking red wigglers not run of the mill garden worm. It gets -15 and colder where I live and no matter what they freeze every year. Red wiggler won’t go more than 6-8 inches down.

    Reply
  • Paul Ornelas says:

    Do you keep the lid on? Is there a lot of condensation? CAREFUL, when you take the lid off there may be worms on it underneath. some might fall off. But first put the worms back in the soil if there are any on the sides and lid. So leave the lid off a couple of inches.

    Reply
  • I thought I’d chime in here, hoping maybe something I say will help someone, or inspire other ideas.

    I live in Maine, so it’s definitely very cold and snowy in the winter. – 20 to -30 degree windchills are semi common so heating worms can be difficult, or just plain expensive. I used to use plastic bins/totes, but now I have a 70 square foot room I built for my worms in my garage.

    METHOD 1—Since I grow an assortment of things all year long, I decided to use MH/HPS grow lights. My garage floor/first floor ceiling are extra protected with boards, tarps, and plastic. Good for insulation, and not rotting out the floor. The top of the worm bedding is covered by black plastic. I then put plant pots on top of that with a couple 600 watt lights (I dim them on warmer days). The lights grow my plants, and keep the black plastic warm which warms the bin. If I have no plants on top, I can lower my lights to about 12 inches above the plastic and it heats the plastic to 110-120 degrees Fahrenheit.

    METHOD 2—RISKY!!! I throw some Alfalfa pellets/green plant material in the bin (blood meal would work too). I either mix some in the top 2 inches, or I mix a good amount into a few holes in the bin. This causes the bin, or the holes to warm compost with the added nitrogen. This is very risky and requires knowledge and practice with hot composting. Too much nitrogen and your worms will cook. Hence, why I only do patches, or the top layer. The worms can surround the hot spots but if you mix up the bin, the whole thing will be hot.

    METHOD 3—This is an experiment I’ll be doing next winter. I sometimes compost in 45 gallon bins. When I mix manure and Alfalfa, then add a jug filled with a gallon of water to the center of the bin I can heat the water to ~130F. I’m going to pump that water through a hose that’ll coil around the worm bedding, pumping warm water all around it. Of course the water will cool but I’m still hoping it’ll stay above 90 degrees. I’ll most likely use a fish tank style pump, but as a fun experiment I’m going to test using anaerobic composting in containers, and use the gas pressure that builds to pump the warm water through the Hoses. One day I may even collect the methane from the anaerobic compost and burn that to heat water, but that might be a year or 2 away.

    Anyway, I hope something here helps someone or gives them a brilliant idea.

    PLEASE ALWAYS be careful when using any electical/heat/gas source.

    Reply
  • My worm bed is made out of a old upright freezer I have about a foot of dirt in the bottom then shredded paper and cardboard then I got peat moss and shredded paper and cardboard at it has a covered area I’m in Mississippi it does get cold but not like up north but do I need to put a heat lamp in it or should what I have will keep them alive in the wintertime

    Reply
  • Hi, great advice, thanks. I’m a wormery newbie and it’s been great the last few months the worms have duplicated and seemed happy in a large plastic storage box off the ground with a lid. However, it’s November in the UK and the temperature has dropped suddenly. I fed my worms a few days ago and left them to it whilst I concentrated on my fish and succulents [newbie to succulent growing as well] and trying to get the lighting and temp right. I checked today and sad. I can’t see many worms and the worms I could see are stiff and hardly moving and for the first time it smells! Which I think means a lot of my worms have died. The springtails I have in there are duplicating probably because the worms haven’t eaten the food as quick. I’ve put a long 2ft rubber water bottle on the cardboard at the top for now and the idea of the seed tray warmer [I have one] is appealing. I also thought of burying a glass jar with water and a pond heater I use for quarantine tanks for fish to warm up in the soil. I will insulate around the container, but can’t face having it in a conservatory with all those flies in the bin, with my succulents in there. Just in case they spread into the house. Thank you for the article and the helpful comments much appreciated.

    Reply

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