Dan, I've tried at least 3 times to grow Echinacea here in Florida. They do fine in the dry months then peter out once June hits with the warm humid nights and the rain. We have well drained soil and lots of sun, but I think it's the humidity that gets them. I was trying to grow White Swan which is one of the old seed varieties.
I've grown some hybrid varieties in my daughter's garden in Salt Lake, and they did last maybe 5 years, with some re-seeding themselves. But not here. Nuthin, nada.
The same thing happens with Agastache, another hot dry summer lover. Bloomed their hearts out from Feb. until June then petered out.
