MSU Horticulture and Student Organic Farm

for winter harvest has been used for at least 15 years but is much less common than season extension. Winter growing and harvesting from passive solar greenhouses (PSGH) combined with the use of cold storage for vegetables (potatoes, onions, squash, carrots, cabbage) has been used for 6 years for a 48-week Community Supported Agriculture (CSA) program at the Michigan State University Student Organic Farm (MSU-SOF). The methods of Eliot Coleman and other farmers have been used to produce a wide range of winter crops in East Lansing, MI, zone 5 and one of the lowest winter sunlight areas of the northern US. Season Extension protective structures can range from cold frames to row covers (low tunnels) to walk in structures (high tunnels) to full size unheated greenhouses (hoophouses). The structure is protecting plants from excessive wind and rain as well as providing protection from frost. A row cover or greenhouse cover can trap the warmth of the soil, which is normally lost to the atmosphere, in much the same way that cloud cover can keep the earth warmer at night. There are four key aspects to the winter harvest in unheated passive solar greenhouses. 1. The first is the use of cold tolerant crops that can handle repeated freezing and thawing. Examples include baby and head lettuce for salad greens; spinach, chard, kale and other leafy salad greens as baby leaf for salad or for cooking greens, as well as root crops like carrot, radishes, turnips and beets. Leafy crops wil