It’s all about season extension up here in Montana, and these cold frames are one of my primary means of making the most of what I’ve got. I build them a little more than five years ago (Nina was pregnant with the twins, who are five now) and they work really well for a couple of reasons. One is that they’re just outside the back door. This early in the season, I put flats out during the day, but bring them in at night. It’s just too cold, and I don’t want to risk losing the seedlings and having to…