number : 6 tot 9 per m2
- little groups of 3 to 10 plants (B) - groups of 10 to 20 plants, even more (C)
Plant description
They like a sandy, well drained soil, not too damp. They do well in rather small gardens, in a border or rock garden.
Deadhead to prevent self-seeding in environments where it may grow aggressively.