I would co-ordinate the setup of the bin to make the first harvest the last. Remove the worms and setup an indoor bin for the winter. Way too many problems keeping warmth and even so, the worms will not thrive outside in Mn. Indoor bins do not have to be a problem.

Chuckiebtoo

A friend of mine successfully overwintered a worm bin in our area by placing it in a depression in her garden and then enclosing it (four walls plus a roof) with strawbales. Our winters are warmer than those in northern Minnesota (we only have a few days each winter below 0 degrees F) but it's possible this might work in MN.

Standard practice here is to put the bin in your root cellar during the winter.

Miranda

My opinion ... if you are thinking about an outside bin dig it in. Initial setup is a pain ... however being buried has alot of advantages. Steady temp through the summer. Place to escape during colder times. Fewer fluctuations. Can have a much larger bin.

Insulating during the winter is also a good idea. Worms can survive in windrows during the winter. The snow will act as insulation.

As long as food is buried I have never had a problem with gnats or fruit flies (however i do freeze all foods before putting them into the bin). I keep a cultivator next to my bins to make sure i have a non lethal digging utensil ready at hand.

One other option is that the bigger the bin the more able it is to handle fluctuations. In a large bin the frozen outer layers will help to insulate the inner parts.

In winter its the north winds that you are most worried about. A bin placed on the south side of a structure will help to keep the temp up by about 5 degrees.

The last option i can think of is to keep it inside a structure, like a shed or garage. This will help to keep the overall temp of the bin up quite a bit.

So i guess after all that rambling ... size and location would be the things id be most worried about in an area with severe winters.

Bryan

I've read about people putting fishtank heaters or fishpond heaters in a container of water(sealed) in the bin. One plan I saw of an outdoor bin for Canada was one with all the walls(and lid) lined with syrofaom insulation.

Hope that helps.

Cass:)