How To Check & Maintain Your Worm Bin’s Temperature

Check Maintain Worm Bin Temperature

We at the Squirm Firm want to help our fellow gardeners with the upkeep of your worm composting bins. We cannot stress enough the importance of being aware of temperature of your worm bin and constantly keeping it under control. Happy worms make a happy gardener!

The Effect of Temperature on Your Worms

The temperature of your worm bin affects red wiggler worms drastically.

  • What if the temperature of your bin is too low?
    • Your worms eat and reproduce less.
    • How to tell with a glance:
      • Your worms mass together in a ball that looks like ground hamburger meat to keep each other warm.
  • What if the temperature of your bin is too high?
    • Your worms eat and reproduce less.
    • How to tell with a glance:
      • Your worms migrate into the cooler lower trays.

If the temperature is too high or low, these effects will eventually damage the overall health of your worm bin. When the temperature becomes extreme either way, your worms will start to die or flee to more moderate temperatures.

The Range of Ideal Temperatures

Red wriggler worms enjoy the same climate as we do. Imagine a perfect day. What is the temperature like?

When most of us think of the perfect day, the temperature is usually between 60-80° Fahrenheit (16-27° Celsius). These temperatures are also the ideal temperatures for your worms.

  • Which Temperatures are Dangerously Cold?
    • Temperatures below 50° Fahrenheit (10° Celsius) will slow down worm activity.
    • Temperatures below 40° Fahrenheit (4° Celsius) will kill your worms over an extended period.
  • Which Temperatures are Dangerously Hot?
    • Temperatures above 80° Fahrenheit (27° Celsius) will slow down worm activity.
    • Temperatures above 95° Fahrenheit (35° Celsius) will kill your worms quickly.

Temperature Maintenance

We’ve impressed upon you the importance of worm bin temperature maintenance and given you the ideal temperature range for your worm bin. Now, we will impart some crucial tips on how to check and maintain the temperature.

Checking the Temperature

We recommend measuring the temperature inside the worm composter with a soil thermometer since the temperature of the bedding is usually cooler than that of the outside air.

We offer a thermometer that is especially designed for worm composting. It has an 8″ probe and is color-coded so you can quickly determine the action(s) you should take with just a glance.

Increasing the Temperature

  • What can you feed your worms to increase the temperature?
    • Foods high in nitrogen as they generate heat as they break down.
      • Lentils, mushrooms, peas, leafy greens, tofu, broccoli, cauliflower, beans, and oatmeal.
  • How can you protect your worm bin from the cold?
    • You can protect your worms from the cold by insulating the composter.
      • If your composter is on a cold surface, then place a sheet of cardboard underneath it.
      • Wrap the composter in insulating material such as wool, cardboard, or other fabrics to protect it from drafts.
    • Warning: Do not wrap your worm bin too tightly with these insulation materials. They could restrict airflow, which can be harmful to the health of your red wriggler worms.
  • What are other ways to increase the temperature of your worm bin?
    • To increase the temperature of your worm bin, provide a heat source for the worms.
      • A heat lamp or a spotlight will work well to warm the bin and provide an incentive for your worms to migrate to the top of the bin to eat.
    • Tip: Keep the lid of the bin on tightly if using a spotlight because worms will shy away from bright light.

Decreasing the Temperature

  • Where should you avoid placing your worm bin?
    • To make sure the temperature does not exceed 80° Fahrenheit, never place your worm composter in direct sunlight.
  • How can you keep your worm composting bin cool outside in hot weather?
    • If it is necessary to keep your worm bin outside during all seasons of the year, you must keep it cool during those hot summer months. Make sure to find a shady spot with good airflow and keep the bedding moist.
  • The temperature of your composter is too high, what can you do?
    • To cool the compost, you can place 1/4″ thick wood pieces to separate the trays.
    • If this doesn’t cool the bedding enough, we recommend adding a fan to lightly blow on the composter (make sure to keep the bedding moist.)
    • Use ice to cool extremely hot worm bins. Only do this in emergency situations as it can make your compost too moist and cause water to leak out of the worm bin.

We hope that this comprehensive information about the temperature of your worm bin helps you stay a happy, healthy gardener with happy, healthy worms! Pick up a worm compost thermometer today if you don’t have one already, and share this page with everybody you know that uses worms to compost. Nobody wants to hurt their worms by accident! Happy vermicomposting!

Article by Donny B

Readers Comments (15)

  1. I added some drunken composting mixture and the 70F increased to 120F by next day. The insulated compost bin is 4′ x 4′ and 4′ high so I believe only the top layer is affected. From about 40 earthworms I added when I started I now have thousands so I probably killed some unfortunately but as the bin is high the bottom layers will protect the downward migrants.
    I plan to remove the top 6″ -12″ of compost and let it cool down then add it back later.
    Net result I may use the drunken method for raw greens then when it cools down add it to the compost bin already partially composted.

  2. I’m in the UK and have had a wormery for 1 month and things were going fine but we’ve just had a heatwave for a week. I moved the wormery into the coolest room in my house but it was still 27 degrees C, outside was 30+ Lots of the worms died and lots kept going to the sump, presumably as it was cooler and drowned in the little bit of water there (below the drain tap level. If global warming is getting worse and worms can’t tolerate these temperatures, then what can be done? Are there worm species that cope with higher temperatures?

  3. I had one time heat wave with temperature of 40 degrees, the warms gathered to ” ground hamburger meat” and survived

  4. I think I’m going to have to find a way to convince my husband to let my move my worm bin inside. I live in the desert and we’re averaging about 108*f during the day, and 90s in the garage where I keep my worm bin.
    Any ideas on how to keep my bin cool (If any of my worms are even still alive… which isn’t looking good) before I precipitate my divorce?

    • Hiya Christine, things are gettin’ hot, huh? Okay, here’s what my easiest suggestion is. Frozen water bottles wrapped in a cloth napkin or washcloth. You’re going to have to donate a napkin or washcloth to this for the duration of the heat. That and maybe 4 water bottles. If you have a tower-style worm bin, add 2 of those water bottles to the uppermost tray. IF you have a regular storage tote, go ahead and scoop out a little spot for them to lay in the top layer of bedding. As the ice defrosts, it will both cool the bedding and surrounding air while, causing cool condensation to drip down through the bedding cooling things as it goes. Make sure to keep your bedding nice and moist in general so it can absorb and maintain cooler temps. Good luck to you, your worms, and your husband!

  5. My worm tote is in the garage, but temps were close to 90 inside the worm bin when the outside temp was around 100. Read about ice packs, but didn’t want to add all that liquid. We have several blue ice packs, so I freeze those, and swap them out twice a day. Temp drops to around 78 degrees inside the bin. I lay a brown grocery bag on top of the bedding, then the ice packs inside of a ziplock bag, on top of the paper bag. Worms like to congregate right under the paper bag because it’s cool and moist. They seem to like it, and I don’t have to worry about the bin getting too hot.

  6. Had a litteral desert type world ending scenario with my worms last summer, they somehow magically survived from end of April(when I got them) to the end of summer with sloppy(at most) care… now they are probably hundreds, but its now damm winter and I opened my compost for one sunny day, the next was raining and now they are icecubes… well sort of… I insulated the entire 1m3 bin in a few layers of styofoam, north is about 20cm thick average, while south is less… they had a bacchelor party every day as far as I am aware up to this point in time in the winter… hopefully the “meatburger” saved them. Anyway… styrofoam is good, if you have a construction site nearby, grab some waste and build a “lego” box around them and wrap ‘loosly’ with packaging ambalage… They will party like its the end of the world in that warm, moist…. you get the picture…

  7. An idea for those of you in very hot areas where it’s even 90 in the garage…try putting rigid insulation board around your bin. You don’t necessarily have to build a frame–though you could if you want. I used it under my box when I had it in the basement to insulate it from the cool temp coming up from the ground through the floor. Or you could use a recycled ice chest. I’ve seen people use an old broken freezer for a larger bin.
    When I lived in San Diego I had a very successful worm growing area right in the ground under my rabbit hutch. I dug a trench under the hutch between the legs then filled it w bedding. Then I did the typical feeding of food scraps in successive areas starting on the left (for example) and going across. By the time I got the the right side, the food was eaten up on the left. The old worm guy who sold me the worms to start w, said that the female rabbit urine stimulated them to grow rapidly. I’ve never seen that written about anywhere, but I’ll tell you what, the worms went nuts!
    Good luck and have fun!

    • Hi Larry!

      Thank you so much for this useful information! We hope to hear more from you!

      • Lawrence Andrews May 4, 2022 @ 5:47 pm

        … Always thinking of ways to improve things and address challenges… For worm farmers in extreme desert areas use shade, moisture and insulation to your advantage–in this way– to keep your bins optimal. Dig a hole 2 to 3 or more feet deep. The earth is cooler the deeper you go. Choose an area out of the sun, in the shade of buildings, solid fencing, dense trees etc. Saturate the soil all around the hole, place your bin(s) in the ground then place insulation board, old carpets, straw etc on top for more insulation. Have fun!

  8. If all the the worms in my compost die due to the heat (in a wheelie bin but in shade) Is it just a case of cooling it down, waiting for more suitable temperatures and buying more worms?

    • Hi Reg,

      If all of your worms die, the remains can be hard to find once they dry out since they are mostly water. As such, you will need to buy new worms to start worm composting again.

      The ideal temperature range for red wiggler worms is between 55 degrees and 77 degrees Fahrenheit. When it comes to maintaining the worm bin, we cannot assume that things are in order simply by appearance. That is why we need the aid of accessories such as the thermometer to ensure that nothing is amiss.

      Check out our blog post here to know more about checking and maintaining the temperature in the worm bin:

      If you have any other questions, feel free to send us an email at

      Best of luck with your worm composting project.

  9. Tahir Ehsan Malik August 27, 2022 @ 11:48 pm

    I started commercial Vermicomposting in Pakistan using manure as major organic material. The climate is hot and dry during summer and humid and hot during monsoon months, OAT rises to 47-50°C. From studies and local experiences following may be tried to mitigate effects of high temp.

    Protect from direct sunlight use top cover with 90 or 95% nursery plastic sheets. A cheap solution. Grow Junter (a long local thick seasonal grass which grows very fast) on the soutwestern side of the beds to protect from low sun after mid day.

    Use walking windrow method or continuous vertical flow method for large scale composting.This way worms keep moving forward/up, away from the expected hot spots, after composting the finished compost anyways is cooler at lower levels.

    Always use pre-composted manure mixture to keep internal temp under control, it is humus has more air pockets and generates less heat inside the pile.

    Cover the bed surface with jute bags, rice or wheat straws and keep them well moist during the day to cool down beds thru evaporation.

    Use mist fans to keep the moist air circulating in the area this will keep the temp down.
    Best of luck.

  10. Hi Reg,
    I am in commercial vericomposting in Pakistan using Red Wigglers and manure as the basic organic material. The climate here is hot and dry during summer and hot and humid during monsoon months. I struggled a lot with hot temperatures between 45-50°C. Thru Studies and experimentation I have devised certain cost effective methods which may be useful for people vermicomposting in hot regions. I would appreciate your inputs to make commercial projects feasible in hot climatic conditions.

    Top cover with nursery cloth providing 90-95% protection against direct sunlight. It is a cheap solution.
    I grow long thick local grass (Junter) on the southwestern side to protect the beds from low evening sun which is very hot.
    Use pre-composted manure mixture as it is humus, cooler, generates lesser heat
    is safer and ready for consumption by worms.
    Walking windrow or continuous vertical flow pile methods are best suited for hot climates as disaster can be averted with min damage. Lower/front areas are cooler, worms move up and forward after composting and are in a safer region where temp can be controlled.
    Cover the bed surface with well moist jute bags,rice or wheat straws to provide cooling thru evaporation. Sprinkle water at least 3-4 times over these covers to keep them moistened.

    Use mist fans (again very cheap remedy) to circulate moist air over the beds. One fan covers about 250-300 sq ft bed area.
    These measure should help to keep the worms safe and working during summer which are long here April to September.

  11. KATHLEEN M GUINSES September 5, 2022 @ 2:45 am


    I’m in Southern California and we have had severe heat waves for over a week. I have my worm bins in the garage. I purchased the worm thermometer and it’s 81 degrees inside each worm bin. I have been putting blue gel packs but did not have enough. Here are my questions:

    1. Will dry ice packs hurt my worms? This is what I have been using along with the blue gel packs to keep the worm bin cool.

    2. If the worm bin is around 81 degrees, do I need to use the additional gel packs to lower the temperature in the bins even though it’s over 95 degrees outside of the garage?

    3. I haven’t fed my worms in over 10 days, will this kill them?

    Thank you,


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