Mindy, thinking about cold winters is hard to do when living in Georgia, but I vaguely remember Yankee winters.
Does the plant room have electricity? If so, would it be possible to use a heatlamp or something to keep the worm-bin area above freezing? (if you have chickens, you should be able to picture what I'm thinking in my head but can't find words to describe - big metal globe with standard lightbulb that clips on things) Or build a box that is larger than the worm-bin and use straw as an insulator between the sides of the box and worm bin?
Just some thoughts, with no expertise to support them (but I rarely let lack of expertise stop me from sharing my thoughts
)
as an aside, thank goodness for the preview feature... touch typing only works if you start from the home keys. Otherwise you wind up describing a "bit metal glove" instead of a "big metal globe"