Even my dwarf gets over 6 foot tall. If you cut it back it will grow back but may not get anymore flowers before winter. I have a couple hummers that visit mine several times a day, also butterflies. I see them kept trimmed back as hedges and they still flower, but those are probably the dwarf, I'm sure at one point they don't trim them so they will flower, late summer and fall is when they look the best.
I had one that was labeled dwarf, but it wasn't and turned into a tree, even with freezing back and hacking it down if it didn't freeze, it would come back and grow to over 12 foot tall each year. I had to finally remove it, wasn't in a good spot for a tree. Made me sad because it was much prettier and had more beautiful flowers than my dwarf does. When I would hack it back in the spring it would rebound quickly but took several months till it started flowering again.
