Well, Jim, here's one report of F. imperialis to the east of you. I've had the yellow form in my garden for perhaps 10 - 12 years, maybe more, don't remember. They don't even get a full days sun & they increase slowly every year. Until last Fall? maybe the one before, I had never disturbed the clump & the ones I moved seemed to do fine. Every other batch of F imperialis I've tried has lasted a year or three & then disappeared. I don't bother anymore to order any outsiders as I'm nervous about possible viruses etc. Hope I haven't jinxed myself now. Robin Bell Zone 5, Ithaca, NY