I have several of the New England Asters and they grow so tall that they flop over. They are in mostly shade, they do get a little afternoon sun. I was wondering if they can be cut back now? They have woody stems and the oldest one is so tall its already flopping over. Another one is still standing tall and straight for now but it to will flop over soon. They are the blue ones. My pink/red ones don't do that. Now that I think of it the pink/red ones are in full sun. Would that make a difference?