Hi Calin, I believe the zone 5 based on some of the sites that note it. No direct experience though. As I understand it your climate is similar to mine though a month off. Winters wet, dry, frigid, cool and everything in between. I've been struggling with planting out Arisaema for a few years and so far have had the best luck under a blue spruce which stays fairly dry over winter. I've been debating potting most of the survivors up and storing them in the detached unheated garage.
