Blue Moon is a pretty rose, I agree. I bought one about seven years ago from Amity. It has been struggling along for all of these years, and it's still alive, but I wouldn't call it a thriving rose. It produces two or three blooms a year and is only about 10 inches tall (after 7 years in the ground!). It's one of the first candidates for removal from my garden if I need the space for another plant.
Mine is an own-root rose, and I'm sure a grafted one would do better, but it's definitely a hybrid tea that needs to be grown in zone 7 or higher. HelpMeFind's default zone is 6, so if it says a rose is hardy only to zone 7, you usually can believe it.
Rose (Rosa 'Blue Moon')
Koelner Karneval (Blue Girl) is hardier and will survive without winter protection in zones 6 and higher. This isn't the HMF default zone 6; it's actual information provided by growers. I don't know how this rose does on its own roots. The only one I have is grafted, and it's about 4 feet tall.
Rose (Rosa 'Koelner Karneval')
