I put in a number of roses last fall, all of which said they were hardy to zone 4. I live in 5a. Home Run, whose literature says zone 4, is the only one that did not come out of the winter, during which the roses were frozen into a snow bank, growing well. I actually decided that it was dead and was about to dig it out when I saw a tiny leaf coming up from the root. It now has about 4 leaves as it does not seem to be going about growing with great enthusiasm. However, it is an own root rose, so I am willing to give it some more time. I would, though, question whether it is really viable in zone 4.