It started with a roadtrip from Southeastern Minnesota, headed west, nearly to the South Dakota border. My sister, Liz Belina, a curious and inventive gardener, had already created a very productive series of raised garden beds outside her back door in rural Peterson, Minnesota. But Liz is a gardener who looks for ways to push the limits of her Zone 4 climate. So when she heard about a tour of an energy-efficient winter greenhouse – one that could be built with materials readily available from a hardware store, heated almost exclusively with stored passive solar energy, and allow her to grow salad greens all winter long – she had to know more.
