Cool season, annual brassica traditionally grown for its spicy seeds. Germinates quickly on a wide variety of soils; not tolerant of wet soils. Tolerates some drought stress, but intense heat during flowering reduces seed-set. Sensitive to frost and winter kills easily. Use between commercial crops and in home gardens as a green manure to naturally fumigate soil nematodes and pathogens. Wait at least four weeks after plowdown before planting the next crop. Has been used in environmental phytoremediation to remove toxic heavy metals such as cadmium (Cd) from polluted soils.