Hi, Ed. Welcome to ATP.
I've never applied bone meal to established roses. I occasionally add a half-cup to the soil mixture when I'm planting a new rose, but never afterward.
From the research I find on the Web, it's not a good idea to apply bone meal to established roses unless your soil is known to be deficient in phosphorus. If it has sufficient phosphorus, bone meal applications are more likely to hurt the rose than to help it. If you have tested your soil and have learned it is deficient in phosphorus, however, you would apply the bone meal twice a year -- in spring and in fall.
