Chelle, I bought an aluminum-framed greenhouse for protection of potted plants that need a cool, dry winter. It hasn't been totally successful. I added insulation, an electric heater, and water-filled bins for passive heating, which combine to keep the interior just around the freezing mark on the coldest nights. The problem is, as soon as the sun hits the greenhouse the temperature inside rockets up, and the extractor fans can't cool it fast enough. Someone always has to be home to manually open the greenhouse windows and doors on sunny days, otherwise the plants cook. I bought some automatic vent openers, but discovered they are designed for summer use and don't operate until the temperature reaches 80F! I now use the greenhouse mostly for cacti, as they are forgiving of wildly fluctuating temperatures. The following are some pics from 2009.
