A cool-season biennial crucifer (Brassica oleracea var. gemmifera), which is of northern European origin and belongs to the plant order Capparales. The plant is grown for its small headlike buds formed in the axils of the leaves along the plant stem (see illus.). These buds are eaten as a cooked vegetable. Cultural practices are similar to those used for cabbage; however, monthly mean temperatures below 70°F (21°C) are necessary for firm sprouts. Brussels sprouts are moderately tolerant of acid soils and have a high requirement for boron. Popular varieties (cultivars) are Half Dwarf and Catskill; however, hybrid varieties are increasingly planted. Harvesting begins when the lower sprouts are firm and 1–2 in. (2.5–5 cm) in diameter, usually 3 months after planting. California and New York are important producing states.