This U.S. industry comprises establishments primarily engaged in growing food crops (except mushrooms) under glass or protective cover. Illustrative Examples: Alfalfa sprout farming, grown under cover Melon farming, grown under cover Fruit farming, grown under cover Vegetable farming, grown under cover Hydroponic crop farming Cross-References. Establishments primarily engaged in growing mushrooms under cover are classified in U.S. Industry 111411, Mushroom Production.