one year we had a freak snow storm at the end of september, the ambient temp was 26 for two days and then warmed up to 62 on the third day and all the snow melted right away we were sure we lost it all because it was bitter cold at the first but when we hiked in to look we only lost about a quarter of our girls, another quarter were frost burnt but alive and the rest were discolored but otherwise fine. the slower flowering ones took it a little worse, but i cant say that is some kinda rule, just an obsevation.