Is it possible that’ Frau A. von Brauerrose’, which is a hybrid Wichurana-according to HMF, can have a resistance USDA 2b? Boodline does not indicate such a potential. Any way anyone had dealing with this rose?
Short answer, NO. Looking at the two parents, I doubt it is much better than R wichurana good to maybe 0 F or -15 C. Crimson Rambler is not much hardier. The polyantha with multiflora blood, maybe somewhat more. Somewhere on another thread I mentioned the work of Rajashaker who found that deep supercooling sets a limit of -40 C for all roses tested including multiflora and wichurana which are not able to get close to that limit.
Zone 2a would be a real stretch with that parentage unless the plant were covered with deep snow throughout the winter. Zone 4b seems a lot more likely as the lower limit, and probably zone 5 in winters without a lot of snow cover.
In my experience anything with alot of R. wichurana blood in it has always had at least some die back every year and I am not even close to zone 2. For example Newport Fairy has a similar parentage and always die backs at least a fourth of the way down without protection.
Thank you for your opinions. Rather any wichurana can not be more resistant than 5 zone. On the other hand, I found this rose in Serbian nursery. It is on the way now. I’ll see how it will endure temperature jumping in January:)