I don't know anything about eastern species, but universally all plants must reach certain temperature requirements to develop their annual cold tolerance. I forget exactly the triggers, I believe the first is frost, and then there is a second phase that puts it into a cold tolerant phase. The same for the spring, but in reverse. So I don't know what the weather has been like her, but its been warm all winter so the plants are coming out of dormancy. If we get hit with frost now, they're going to lose a lot of new tissue.