Don't throw the arrangement away when you're finished. Let the flowers dry completely and then scatter the seeds around for a denser planting. I try to preach patience when growing perennials and roses - they get better with a little age. The same is true with purple coneflowers. More flowers are produced in the second and third years.
Purple coneflowers are perennials whose clumps can be divided in the fall when necessary.
This may not need to be done for three or more years. It also can be propagated from its own seed. After you grow purple coneflowers for a few years, you will wonder how someone could name such a pretty flower after a hedgehog. At least they didn't stick the name weed on the end of it. Norman Winter is a horticulturist with Mississippi State University's Extension Service.