Kale is technically a biennial, that is, it grows vegetatively the first year, then blooms and dies its second year. In Illinois it is typically grown as a cool-season annual because most winters it will not survive. It tolerates temperatures down to the low 20s above zero, but usually dies when temperatures go lower than that. Occasionally with good snow cover or heavy mulch plants will survive Midwest winters. But after the cold of winter, the plant is programmed to send up its flower stalk, bloom, produce seed, and die.