Deep winter greenhouses

UMN Extension hub on deep winter greenhouses (DWG): passive-solar, east–west structures with steep south glazing and fan-driven underground thermal storage — related cold-climate season extension but distinct from pit walipini excavation. Defines DWGs as passive-solar greenhouses using sun as primary heat source. Built east–west with steeply sloped south-facing glazing to capture solar energy on coldest days; solar-heated air drawn underground with a fan and stored in insulated soil/rock thermal mass for night heat. Intended for small- and mid-sized vegetable farms in northern cold climates; farm-scale prototypes partnered with Minnesota farms. Crops suited include lettuces, herbs, brassicas, Asian greens, and sprouts (cold-hardy, lower-light).

RELATED BUT DISTINCT from walipini/pit greenhouse: DWG is not primarily an excavated pit; heat storage uses ducts/thermal battery rather than full earth-sheltering of growing space.

extension_guide|candidate