Pacific Northwest Gardening: Plant protection below freezing, 2 by Pistil

Pistil wrote:
Hi mhf
I too always seem to have things in pots I need to keep alive over the winter. Here is a photo of my little polycarbonate cold frame I bought about 20 years ago. The plastic has gotten a bit cloudy. The nifty automatic opener device still works perfectly. It has a "bimetallic" piece of two metals stuck together, that shrink and expand at different temperatures, so it bends upwards when it gets to about 72 degrees, then closes when it cools off. It has just enough strength for the light plastic cover. No batteries or electricity or timers. Genius!
I put my little plants in a very protected corner with a fence and overgrown hedges on the south and west, where the weather comes from. You can see a few bigger pots that would not fit, but they survived. You can see the Japanese hollies are growing up out of it.