Zone 6A, Cincinnati Ohio. We are coming out of the hardest winter in years. 7 year old tree that has done fine heretofore has not survived. I didn't track our lowest temp, but no colder than maybe -12. The tree survived a night of -16 two years ago, but that was 1 night. This winter saw a period of several DAYS at or below zero. I guess that was just too much for it. Time to replace it with a pie cherry.