I have done this too, but the secret with roses is moderation. There is a fair amount of nitrogen in coffee grounds. Like mulch, the organic material must break down first before it becomes useful to the plant. Organic is best in the long run but it is rarely a quick fix. Earth worms love coffee grounds. Also I have become a believer in alfalfa. Buy a 50# bag of pure alfalfa pellets at a feed store. It's cheap. Put two handfuls around each bush once a year. Within a month you should notice more growth or basal breaks. Try it but everything in moderation.