This hedge, for lack of a better word, of pagoda started from a SINGLE plant. Now its a hedge. I am in 9A as well, although sometimes it feels like 9B or even 10A. Also behind this hedge is the Clero with the white rosette flowers, probably the one you are calling Cashmere Bouquet. Those are horribly invasive. These plants freeze to the ground every winter almost. But they don;t die completely...ofter, the lower stem is even still green and growing while the top is dead. I have to come out and trim each and every one back in the spring. And they have the annoying habit of running under the greenhouse wall and coming up inside the greenhouse. I pull Cleros out in there on a daily basis. These are considered old growth now, they have been here over 10 years, and they get easily 8-9 feet tall every summer
