We've had multiple frosts now, and while the mini greenhouse is doing great, the Brussel Sprouts don't seem to be moving along quickly enough for a harvest before they freeze completely. I believe they're too deep into the shade, as the low winter sun is giving less and less full light to this end of the yard. I had planted them too early in Spring, put them in the shade to protect from summer sun, and now have pretty well screwed the pooch. Next year I'll start my seeds later, and plant them in an area with more winter sun. Lessons learned!