Pete,
Mine actually have topped out the past two year around 10'. This year they are right at 9' now... This topic has been discussed on this board only a couple of weeks ago... Here's a link to the thread:
How did bigdog get his velutina to flower that small
Whatever the reason is, mine tend to grow alot bigger than some of the other ones that I have seen... Most nurseries list their velutinas to grow 4-6'. Who knows, all I know is I sure enjoy my clump...
Randy