This true perennial can be treated as an annual, producing an abundance of 2in chalice shaped blooms that smother the dwarf plants. Plant in groups of four, 1in apart for maximum impact in containers and at seasons end, transplant in the border or rockery as a perennial.
Sow from February to late May on the surface of a good seed compost. Germination takes 30-90 days at 22C (70F). Don't exclude light, sealing in a polythene bag after sowing is helpful.
Hang out-of-doors in a sunny sheltered spot. At the end of the season, plant out in the flower border or rockery, 30cm (12in) apart in full sun and ordinary, well drained garden soil.