I can't believe it's been almost a year since my last update! The two surviving bushes are doing great. The bigger one, the one that was already spreading like crazy last year, is still spreading like crazy this year. The other one is more subdued, but it's doing quite well, too, and they're both blooming like crazy. There is one thing, though, that's troubled me from the first time they bloomed: their color is more on the dark pink side than purple. Oh, don't get me wrong, they're very pretty, and they're darker this year than they were last year, but they're still not PURPLE and white, they're dark pink and white. Is there perhaps something they're missing in terms of nutrients? I'm giving them Miracle-Gro Shake 'n Feed Continuous Release Rose and Bloom Plant Food...but I had forgotten to do it for, well, a few months, until today. :)

Sanitizing pruners can be a real chore--I do it every time I notice I cut into something that might be canker, and intend to cut something I don't want to get infected. I find that I can even keep some long canes on HTs--they have vigorous growth with lots of buds. But, if they look like they have used up their "flower power" and only have weak growth, I cut them back in late Spring, to encourage basal breaks, with plenty of time for the canes to harden off before the weather turns cool. Often, roses will tell me where to cut--I cut off canes just above signs of vigorous growth. I'd probably get more roses to exhibit if I pruned harder, but my wife likes to show off the garden, so I compromise between lots of blooms in the garden and a few good stems for the show.

I don't know about the breaking off, but clumpy "witches' broom" growth sounds like herbicide damage or the terrible rose rosette disease. Please post sharply focused pictures, closeup and medium. I doubt that canes are breaking off by themselves. Groundhogs, dogs, children, basketballs etc. can break canes, or heavy rain when the rose is carrying heavy blooms.

If you have to use a fertilizer at planting, the slow re lease type you used is a good one. But, heat causes faster release of the nutrients. If you want to follow the instructions on the pkg of fertilizer, go for it. All we can do is give advice based on our experience. We're not trying to sell or have you use fertilizer. Your roses may grow out of it when the weather improves. Right now you're stuck with what you have. Often when attempting to undo something or add something else to correct a problem, more damage is done. Not having been there when you planted the roses or experienced the weather you have, We can only give an educated guess based on the info you provided.