Tim,
The tallest plants are about 4 feet high. They originated in SC and were transplanted a couple years ago. They made a lot of growth last year.
The shorter plants are about 5 years old and only 2 feet high. The seed source for them was the Arnold Arboretum. I have not fertilized any of them because of fear of winter damage.
The are growing in Bennington Vt.
A plant growing in the warmer location of Albany has always died back substantially until this year when it was moved into the shade and near a fence. It would look good until February when the damage showed up.