I've had Christmas Celebration since 2012. It has not increased much at all. However it doesn't get any sun until mid afternoon. That with the fact it is an evergreen here in zone 5a is most likely why it doesn't preform to its registered statistics. I know if I'd move it into full sun it would do better. That being said, it's a keeper for me. Very pretty bloom. Someday I'm going to make a "Christmas themed" bed and I gotta have that one in it.