Vermicomposting in Winter

On a freezing cold day, it’s hard to get out of bed and get cracking with the day, right? The same goes for the vermicomposting worms in your Subpod. They’re not big fans of the colder winter months, becoming a bit slower and a bit more inefficient. Just like me without my coffee!

The good news with vermicomposting is that while it slows down in winter, it doesn't have to stop! There are a few extra measures you can take to keep the winter chills out of your Subpod and keep your worms comfortable and composting.

The outside temperature doesn’t affect your worms activity, but the temperature inside your Subpod does. So winter composting is all about keeping a nice, warm and regular internal environment for your worms to enjoy.

The optimum temperature for vermicomposting worms, like our favourite Red Wrigglers, is between 12° and 32°C, or 55° to 95°F. So in winter the aim is to keep things 13°C and above. Below that, they lose the will to do anything, and if they’re subjected to much lower temperatures for extended times they ain’t gonna survive. Here’s how to stop that happening:

Change the Subpod Location

Ok, we get many of you will have your Subpod buried in your garden, so it's a little tricky to move it. If you’ve got a Modbed or a Grow Bag with a Subpod Mini in it, getting through the winter months is as easy as moving into a warmer spot. Temperatures are much easier to manage indoors, so find a spot in a spare room or basement in your nicely heated house.

If you don’t have space indoors then a garden shed or garage also works, as they still provide a level of protection from the biting winter winds! We’d just recommend avoiding placing your worm farm on bare cold floors. Also, if the shed adjoins your home, place it next to one of the house walls that will benefit from your heating system.

Internal Insulation

If your worm farm has its forever home buried in one of your outdoor garden beds, you're not going to be able to move it. That’s ok, you can still keep your worms warm through winter!

An easy and affordable technique makes use of natural materials. You’ll need some dry carbon materials like Autumn leaves or coconut coir. As the temperatures start to drop, add them to your Subpod. They insulate the internal environment, trapping in the heat and keeping the cold out.

Keep feeding your worms with food waste, but be mindful of the amount they’re managing to compost. If there’s plenty of food that is going uneaten, don’t add to it. Be patient and let the worms do their thing.

We’d recommend putting coffee granules in with each feeding. These are nitrogen rich, meaning they’ll give off heat as they break down.

Subpod’s Hot Tip for Winter Months: a compost thermometer will help you keep an eye on the internal temperature of your Subpod and keep it at the optimum temperature.

Joseph from Maryland sent in this picture of his winter-ready Subpod!

If you experience fairly mild winters you may get away with increasing the amount of mulch around your Subpod. Do it higher than you normally would around the Subpod, all the way up to the lid.

For very cold winters, consider dipping into the piggy bank and buying a ‘Coldframe’. This is a mini greenhouse that you pop over your Subpod and the surrounding garden bed. It works by trapping the heat inside and keeping chilly wind out, maintaining a nice cosy space for your worms to enjoy.

You won’t get the compost outputs like you do in summer, but the worm farm will keep ticking over and you’ll reap moderate amounts of compost too.  

This method, combined with the above trick of adding extra internal insulation and some coffee grounds, is a winner for sure!

Need More Worm Farm Information?

A heated worm blanket? Sounds a bit science fiction-y! It’s an actual thing though, and we’d really recommend it if you want to keep composting during the winter. A genius Subpod-er from Seattle, Tony Kent, did a deep dive into using heated mats, which you can read here.

Heated mats coupled with the use of a thermometer will really help maintain optimum temperatures in your wormery. Make sure you regularly aerate your compost, and keep an eye on the moisture levels which may become high because of the heat.

Please take the utmost care when running electric cables outdoors. Ensure exposed plugs and equipment like the thermostat is insulated and dry. Tony explains how he does this in the above link.

Tracy Flowers from Michigan had this to say over at Growhub about this technique:

“I followed the heating pad set up for a Michigan winter and my worms are still going strong! I have snow on the ground and my worms are multiplying and devouring weekly feedings.”

Winter Worm Farm Success

Vermicomposting in winter is very possible, and taking on board some of the above techniques will keep your wriggly friends, well, wriggling!

Giordana from Baltimore has been using Subpod for a couple of years now. They’ve managed to get through the winters unscathed, with their worms still providing them with compost. Have a look at her story below. Until next time, happy composting!

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