Answer: The easiest way to keep an ongoing supply of these plants is to allow the best to set seed and reseed themselves naturally. In order for this to provide a continuous supply, however, you will need to have mature plants for two years in a row to establish the seeding pattern. Alternatively, you can purchase (or start new plants from seed yourself) every spring. To assure blooms next summer, you need to plant new plants now.
Q&A Library Searching Tips