Help, My Worm Bin Froze Over the Winter! Now What?

Worm bin froze

I get it. Your life is busy.

Family, career, the home–your workload is endless! So even when you have all the best intentions for the care of your worm bins, sometimes…stuff happens; winter weather descends, worm bins freeze and you’re like, dang, I wish I took care of that before it was too late!

Been there, done that. I’ve left my worm bins exposed to the elements before–with terrible consequences I might add. It was awful. I felt like a worm murderer.

In a moment of gratitude I agreed to let my family care for my worms while I went away for a weekend. I said, “Be sure to always put the lid back on. Bring them in if it gets too cold!”

Well, guess what, keeping the lid open for airflow and to help regulate moisture is great, but only when it isn’t raining. And what’s more, soaked bedding quickly takes on the ambient air temperature, rendering “cozy” impossible when it’s cold outside.

So, with just a little bit of rain and a freak dip into the low 30s overnight, I came home to find that many of my once thriving worms were no longer part of my fertilizer crew.

I’m here to spare you from that kind of devastation.

This month, The Squirm Firm is guiding rescue missions far and wide to salvage what remains of wormsicle compost bins. You’ll learn how to:

  • Understand how frigid temperatures affect your worms.
  • Rescue your worm colony from dangerous cold.
  • Redeem what remains of a frozen worm bin.
  • Protect your worms and prevent mass casualties caused by cold.

Jack Frost = Worms Lost

Unlike earthworms, Eisenia fetida (red wiggler composting worms) do not burrow below the frostline to lay safely dormant below the frostline through the winter. Instead, they stay right up top in the first few inches of soil, leaves, or bedding.

However, just like their depth dwelling cousins, a nice juicy composting worm is about 90% water. Therefore, as winter temperatures fall to freezing, the earthworm remains alive while the surface-dwelling red wiggler perishes. It’s mortally wounded by the formation of ice crystals that damage their delicate skin and organs.

The Silver Lining

Alas, all’s not lost, not even if your worm bin is locked in ice! What may look like a barren wasteland of frosty food scraps and crunchy casts may indeed hold an entirely new generation of compost worms just waiting to grow fat and happy in that very worm bin.

And hey, there’s still black gold in that bin, even if it is frozen solid.

Backup is on the Way!

There’s no disputing the fact that prolonged temperatures at or below 40F will decimate a worm population, not to mention what a full on freeze will do. Unfortunately, a post-mortem red wiggler can not be resuscitated. Their cocoons however, are another story.

As temperatures plunge, Eisenia fetida sense impending doom. It’s then that an amazing protective mechanism kicks in to secure the future of the species. They use what remains of their time to mate and lay as many cocoons as they can before they…you know, freeze to death.

Though the thin-skinned parent worms may die of cold exposure, safe within a protective shell, the embryonic babies are safe. The nearly microscopic red wigglers lay dormant, but not dead.

According to M. Holstrup in the Journal of Comparative Physiology, “Though the red wiggler will perish at temperatures below freezing, some worm cocoons have been documented as having survived at a chilly 7F for as long as a couple weeks, and for up to eight weeks at a balmy 17F.”

So, what if my worm bin is already frozen?

Don’t worry, that’s exactly what we’re here for.

….Your first mission, should you choose to accept it (Yes, YOU), is to revive what lies dormant and prepare for a rapid population increase.

Your second mission will be to preserve and protect the worms’ habitat by relocating the worm bin to a warmer location and/or constructing a well-insulated enclosure.

The Rescue and Revival

If you’ve made it this far, you’ve likely put some heartfelt time and energy into maintaining your worm bin and don’t want to see it go. That’s great! And salvaging it is totally doable. Just follow these steps:

  1. Defrost the worm bin.
  2. Determine the status.
  3. Dry up the bedding.
  4. Sift for gold.
  5. Start a fresh worm bin


As winter winds down and days lengthen, the temperature rises, the earth thaws and life begins to stir again.

But why wait until Mother Nature is ready to bring things back to life? You can encourage your worms to get a jump on spring by simply bringing them into your home, or another sheltered place where the bin can defrost.

Note: I would be lying if I were to say that a worm bin full of room-temperature dead worms is pleasant company. But, nope. Beware, they reek!

So, the first part of the thawing process is really one you may want to let happen maybe out in the garage or in a shed. Your family will thank you. Use a worm compost thermometer to know when the bedding is back up to an ideal 72 F or so. Any surviving worms will be slow but active even in the 40s.

Determine the Status

Once the contents of your worm bin has been defrosted you’ll have a chance to assess the damage. You may even find some worms have survived!

Often within a large volume of worm compost the center will remain unfrozen. Take a look. Living worms will likely be very sluggish but still moist and plump. It only takes two to get a new colony started. It worked for me after my own cold rain debacle!

Also, keep a keen eye out for those amber to maroon colored cocoons. If you find them amongst the bedding, you can be sure you have a new generation on the way. Congratulations!

Dry up the Bedding

Ideally, you’ll want to get your worm compost dried out enough that it doesn’t smell and you can work with it. Drying up the bedding will help you get a jump on not only a new colony, but also on your spring garden.

Once your compost has been dried out, you can go ahead and sift all that black gold to harvest a batch of nutrient-rich fertilizer. Not sure how to do that? Check out our article on how to harvest worm compost and you’ll be set.

Sift for Gold

Sifted compost easily reveals gads of those wee egg-shaped cocoons. A one-eighth inch spaced screen should be sufficient for separating out the finely textured black-gold casts from the little golden cocoons you want to save. If you don’t see any cocoons and no live worms, just be patient. There’s still a chance they are in there hiding.

Start Fresh

Prepare your worm bin as a nursery for the babies. Add plenty of moist bedding, organic matter and, of course, the cocoons. Set the “nursery” in a place where the average temperature is around 70F and you can monitor the hatching. It takes temperatures of between 65F to 85F to initiate the hatching process. Inside your home should be ideal!

In a matter of weeks all viable egg sacks will have been vacated. You’ll find lots of itty bitty worms looking to get busy eating, growing, and churning out vermicompost just like their parents did.

Best Worst-Case Scenario

If you go so far as to thaw your worm bin, dry it out, sift it and find no or few egg sacks, you may be resigned to starting fresh with a new pound of worms. And that’s okay; you can use some of the existing compost as a starter for the bedding that will welcome the new colony.

In fact, with a little patience you may find your worm bin is back to thriving in no time! It only took a few weeks for my depleted worm bin to be back in action as if nothing had ever happened. Amazing!

Preservation Means Protection

You can be sure that next winter’s temperatures will be equally unkind to an unprotected worm bin. So avoid a worm genocide by taking just a few precautionary steps to keep your worm herd safe.

  1. Bury it
  2. Pack it
  3. Put a lid on it

Before a freeze sets in and destroys your worm colony, designate a little section of earth to call their winter home.

  • Simply dig a hole deep and wide enough to accommodate the entire worm bin and a few inches of insulation all around.
  • Place your worm bin into the hole and pack the sides and top with materials that will help retain the warmth of the bedding.
  • Layer insulating material over the top to cover and overlap the entire hole. Place something heavy on the lid so that winter winds can’t blow it away.

With adequate moisture, food, and oxygen a submerged worm colony can be sustained safely through the winter months without risk of freezing. For more useful tips and suggestions, check out our article on how to help worms survive the dangerous winter cold.

For even more ways to avoid common worm composting “trials and errors” you can learn from our mistakes! We share what’s worked best or failed along the way by bringing you tips and tricks in our free newsletter. Keep ahead of the game by signing up now. Just once each month we will deliver the latest worm composting advice right to your email inbox.

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Happy worm composting!

Readers Comments (1)

  1. I think about 2/3 of my worms have died after a week of frosty nights (I live in New Zealand). I’ve brought the bin inside to my unheated hallway which is still warmer than outside and shouldn’t get near freezing. I’m just wondering whether I should remove the dead worms or leave them to decompose? The bedding didn’t freeze as it wasn’t too wet and i’d just added a lot of shredded newspaper just before the cold weather hit. Appreciate your advice! Thank you!


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