How hardy is Indigo Rose?

[Balr14]

Weather here has sucked pretty much since Mother's Day when I planted. Lots of rain and cold weather. Rain almost daily and only about 7 days of temperatures in the 70s or more; mostly 50s and 60s. I have 2 Indigo Rose plants and their leaves are consistently turning blue-black, even lots of the flower buds have this color. I've been pruning off branches with this discoloration. It's even on the sides of a few tomatoes. Other plant, in the same containers, that are touching these are not bothered at all. But I do have a number of plants that show signs of too much water and cold temperatures.