The frigid temperatures here in Manitoba, (today’s high is expected to be -27 Celsius with an extreme wind-chill of -47) are exactly why it’s difficult to raise worms outdoors on the prairies. You can’t freeze a worm. While our Red Wigglers can tolerate a very wide range of temperature changes, it’s often over 25 Celsius in the summer months; they can’t go below about plus 3 or 4. So, what’s the trick?
Size matters, our worms survive because of the size of the active compost heaps where they live. A one ton pile of cow manure can generate quite a bit of heat on its own. With the help of a deep snow pack over layers of clean straw, the heaps will form a protective ice shell that keeps the interior from freezing. How do the worms breath you may wonder and that’s a great question. Think about how fish can survive under a frozen pond… air exchange is greatly reduced but enough can filter through to keep life flowing. The chemical reactions that produce heat are certainly more anaerobic than during the summer months but the worms can thrive on the peripheral of that area and continue with their aerobic life processes. We have never experienced any “winter kill”.
If you plan on trying to keep outdoor worms at your place, you’ll need a very big and active compost to keep them going over the winter months. Red worms lack the instinct to burrow under the frost line like our indigenous Earthworms because they naturally dwell in a different stratum of top soil. Spring would be the best time to get started on an outdoor vermicomposting project, give it some thought and contact us; we’d love to help you in the warmer weather.
If of course you’d just like to carry on composting in your house all through the year, you can always try an indoor bin and we can help with that too.