Jesse- You've gotta keep the rhizomes away from frozen soil. If they wholly, or even partially, freeze, the plant won't come back. I can get them through the zone 4/5 winters here, but the plant never amounted to much so I stopped protecting it!

Thanks paul that seems to be the same as here. It never grew too much in the summer, which leads me to believe that recovery in the summer would be painfully slow. I dont mind having to "help" a plant out but completely babying something just doesnt work with my schedule.

I really should try to get some soil temp readings over the next winter. Some things survive that just shouldnt, like figs, the needle palm, bamboo and crocosmia. I may be able to push zones with some herbaceous plants due to this.