Hi Kath. I'm not sure why you're feeding them so often. It sounds as if that may be the problem. What are you feeding them with, and how big are the plants and pots?

The problem might be that they're in pots, specially if they've been in there for longer than a year. Otherwise, its difficult to answer - a photo would have been useful, because if the browning is happening as the buds open and you've had lots of rain, it could be rainballing, or it could be mildew on the buds causing them to abort, then go brown.

Also all the rain has probably made them go brown. That is what has happened to some of my roses.

I have admit that I hate roses in pots. They like moist soil which is cool and has room to spread their roots. They also seem to get stressed in containers, thus being prone to mildews, blackspot and viruses. I'm with Bamboo; pots are not the ideal, better to have them in the ground.