In most climates, raised beds sit empty through winter when they could be producing fresh greens. What a cold frame actually doesA cold frame creates a microclimate that stays warmer than the outside air by capturing solar heat during the day and providing insulation at night. Cold frames are smaller, simpler structures that sit directly on the ground or on top of existing raised beds. What grows well under protectionHardy greens tolerate cold temperatures and thrive in cold frames through winter. Winter root vegetables, such as carrots, beets and turnips, can remain in the ground under a cold frame and be harvested as needed through winter.