The one I planted 13 years ago got about 15 feet tall and only about 5-6 feet wide - It was still growing taller and not adding any width. Amazing blooms with the first flowering and still really nice the remainder of summer. Pruning does ruin the structure. We had a bad drought and the shrub made it but lost some limbs that I pruned back. No growth to cover it. It just looked like some more open space between branches - thankfully, the way it died selectively choose what branches to have die off, resulted in a very beautiful shrub even after pruning, but significantly fewer flowers. As you can see from the photos from one year to the next. The top photo is the shrub post pruning due to drought) and lower photo is the year prior - what it looked like every year up to then.