Can You Keep Composting Worms Indoors During Winter?
Composting worms can live and process food scraps indoors throughout the winter. In fact, indoor vermicomposting is the only setup I use at Underhill Worm Farm.
We are based in Pueblo West, Colorado, and experience cold, dry, and windy winters every year. Keeping our bins indoors lets us protect our worm herd from these harsh conditions. Plus, this setup makes it easy to do all of my worm farming from the comfort of my home.
If you're considering vermicomposting during the winter, here's what you need to know.
Where Should You Keep a Worm Bin During Winter?
The first step is to find a cozy home for your worm bin. Choose a location between 55°F and 80°F.
Our worm bins are in a heated bonus room underneath our garage. You don’t need a dedicated room like ours, though. A basement, laundry room, closet, or utility room can work just as well, provided the space is ventilated and the bin temperature is stable.
If you're uncertain about temperatures, use a thermometer to check the room over several days before setting up the bin. Once it's in use, check the temperature inside the bin, too.
Does Worm Care Change During Winter?
Not much changes for my bins, since they stay in a heated space.
I still check the bins’ moisture and temperature, and use that information (and the amount of leftover food) to decide when to feed. But that’s something I do regardless of the season.
Let Your Worms Determine the Feeding Schedule
This is something I emphasize in my Vermicomposting 101 workshops: your feeding routine should be dictated by bin conditions, not a schedule.
When I check my bins, I look at how much food remains from the previous feeding. If there's still a significant amount of uneaten food, I simply wait before adding more. If uneaten food is building up and I’m concerned about low-oxygen conditions, I add extra bedding to help balance moisture and airflow. I also use oyster shell flour to provide grit and help buffer acidity.
If you’re keeping your worms in a colder area of the house, you may notice they take longer to process food during the winter. That’s ok! Just remember to always observe and adjust your feedings accordingly.
Can Composting Worms Survive Outdoors in Winter?
It’s possible, but keeping worms alive through freezing weather requires more planning and protection.
Some worm composters successfully overwinter outdoor bins using insulation, larger composting systems, or other measures to protect worms from extreme temperatures.
I haven't overwintered my own bins outdoors, so I can't speak from experience about those methods.
For beginners in Southern Colorado, I recommend starting with a temperature-controlled indoor location.
New to Vermicomposting?
If you're interested in starting your own worm bin, Underhill Worm Farm offers a free Beginner's Guide to Vermicomposting.
The guide covers choosing worms, preparing a bin, feeding and maintenance, troubleshooting, and harvesting worm castings.