We grow quite a few rebloomers, here in zone 5, and usually have quite a bit of luck with them...best I can tell you is *most* need extra TLC, for any real success. I grow them, mostly,in their own beds. Fertilizer schedule somewhat different from the "spring only" irises...more water during the summer. That said, I have some "waifs&strays" planted "here&there", that rebloom, pretty faithfully, with no extra care. "Immortality" seems to do pretty well "by itself", most years, and also seems to need division every 2-3 years, in order to rebloom. I agree, the "form"on "Immortality" leaves a lot to be desired...it's pretty "floppy", but it's a good "starter" Re, as is "Earl Of Essex"