In my daughter's garden in Salt Lake City, we had Victoria Falls and a nice purple called Cantina re-bloom at least a couple of times before they moved away from "my" garden.
I did dig up some rhizomes to bring along but they've only been in a year, and their garden at the new house is not as sunny as the old one. Rebloom there definitely seems to depend upon how early the spring weather warms up, and also how late into fall you get before there is a frost. At that altitude, the cold comes suddenly and it really gets Cold!
