You can do a google search on it, but none of the varieties that I checked are hardy north of z9 or so. They're pretty, though.

i have been growing for years in anniston (z8a). despite the z9 rating, they are perennial here....treat it like a brugsmania aka angel trumpet (in which its related). they performed poorly this year due to drought/heat. i know another local gardener that grows then as well here in central alabama

Thanks plantaholic. That is the kind of input I was looking for. I had spent several hours researching them and could not find conclusive info on their hardiness and I knew y'all would set me straight (-;