I purchased a plant earlier this year and put it in a deep raised bed. It got quite large and was budding when we got our first bad temperatures - it was 28* and it damaged all the foliage. I then covered it at nights in case these temps returned. I noticed that the square stems have split from the freeze and I had not cut the tips or branches. Will the root stock come back if I keep it mulched and cover the top still. I read what Betsy said about hers and realize that this is a guide line as there are always variables in conditions. If it makes it I hope that it would bloom sooner as a more established plant. She said she cuts her back after a bloom also. Anyone with advice I appreciate it. Thank you.