Roses are NPK kinda things, as are most plants: Nitrogen, Phosphorus and Potash. Most formulations you see for roses and for that matter other flowering or fruiting plants are numbers like 5-10-10, lower in Nitrogen, higher in Phosphorous and Potash. We recommend, without hesitation, Mills Magic (available from our supplier directly to you).
Mills Magic Rose Mix is a 100% natural product that combines steamed bone meal, alfalfa meal, cottonseed meal, fish meal, activated sludge, blood meal, and an organic compost activator. NPK analysis is 6-5-1.
General rules about feeding (remember, general rules, not the Holy Grail!): Roses should be fed at least three times a year. If you are using liquid fertilizer, you may feed up to six times a year-use organic fertilizers if possible. Some rose lovers feed when they "dead head" the old flowers, others feed quarterly during the season.
A few easy things to remember:
Check with your local nursery or local chapter of the American Rose Society to identify the chemicals and fertilizers recommended and permitted in your locale. And, as a famous Rosarian stated, "Roses are Pigs! Feed them!!"