Tender perennial that is winter hardy to USDA Zones 7-10. In St. Louis, grow as an annual in average, moist, well-drained soils in full sun to part shade. Tolerates poor soils as long as drainage is good. Seed may be sown directly in the garden after last frost date. For earlier bloom, start seed indoors 6-8 weeks before last frost date. Set out seedlings or purchased plants after last frost date. If sited in sheltered locations with southern exposures, plants can survive mild St. Louis winters. Even if plants do not survive winter, they often remain in St. Louis gardens for a number of years through self-seeding. Plants more freely self-seed in the deep South where they have escaped gardens and naturalized in a number of areas.