figuring out the bloom times of the 3 varieties is where you need to start. randomly "cutting them back" is a bad way to look at it if you're concerned about flowering. spring bloomers will flower on growth that was put on last year. summer bloomers flower on new growth from this year. cutting them back is a crap shoot unless you know when they flower. its good for size control however.
Rosemoor is a summer bloomer, so cutting it back now in order to determine a course of action will probably not harm the flowering aspect. it may delay it though. but as fast as it appears to be growing, I wouldn't worry about it too much!
