Large genus of 400 species of annual, biennial and perennial, herbaceous succulent species. They grow in full sun, in drained, neutral or slightly alkaline, moderate soils. Prune lightly after flowering to restore shape and divide every 3 or 4 years, removing any cut or dead roots, with a view to stimulating a richer flowering. Plant in rock gardens, in arrangements or in flowerpots. Easily propagated by division in early spring.