It would help,
@JenWeb, if you would go into your "Profile" and add your location. City and state are most helpful but even your USDA zone would work.
I can assure you, here in Mississippi, the Shasta will not re-bloom this summer if you cut them back. It is perhaps the heat plus the extremely high humidity, but I really don't know. I have cut many of mine back in mid-summer because they were falling over onto azaleas, and they neither re-bloom nor have a chance to even put on much new growth before the first frost hits.