I've never grown them as a perennial, they changed us from 7b to 8a and I never felt like storing them. The ground still freezes once in a while so conditions are iffy. I grew the mixed border type for my mother and they were cheap and spectacular! Problem was when a storm came up it snapped them off at ground level.
http://gardening.stackexchange...
The last couple of years I ordered bulbs and I did not like them because they were unpredictable. Most need to be staked because they flop over when they bloom. Not a real problem for gorgeous blooms but I just hate digging them up for winter and I hate not knowing if the ground will freeze or not. I've never had any come back because they either freeze or rot. They are so ratty by fall, I just toss them and buy new ones in spring if I decide I want some.
http://www.ask.com/question/ar...
This above link explains it best I think. They are native perennials in Mexico.
http://www.swallowtailgardense...
