Yield of Leafy Greens and Microclimate in Deep Winter Greenhouse Production in Minnesota

The Deep Winter Greenhouse (DWG) uses passive solar technology to create an environment where cold tolerant crops like leafy greens can be grown during the winter to satisfy consumer demand for fresh local produce year-round and increase revenue for farmers. A cultivar trial consisting of 12 different salad greens was conducted in partnership with three farmers in order to determine suitable cultivars for these unique systems. Yield and days to maturity were recorded, and microclimate conditions such as light, temperature, and relative humidity were tracked throughout the season. This study included three sites from three distinct locations within Minnesota. Environmental differences among the DWG sites and within site replicates were observed. Yield also varied with micro-climate. The trials demonstrate that lettuces and greens such as ‘Florence’ (Lactuca sativa L.), ‘Salanova’ (Lactuca sativa L.), and ‘Vitamin Green’ (Brassica rapa L.) generally grow well. These cultivar trials, coupled with other horticultural trials and economic analyses, will better inform recommendations for farmers growing in these unique environments.