Your question is a little difficult to answer with any authority since it really depends on the make-up of your soil. We live here in the western U.S. and have kept roses for many years. We have a typically western soil that tends to the sandy.
A good, over-all mix will be in the area 12-16-12 (as annotated on the container). I prefer a product called Jobes' Rose Fertilizer Spikes. These are slow release, which is desirable for all roses and come in a "spike" design that can be puched into the soil at the base of each plant. They're economical as well. I use two per plant at the beginning of the growing season... (Early May for us). They last about two months and then I use one more in mid-summer. If my Old Farmer's Almanac say's it's going to be an extended Fall, I might put in one more sometime in September. It's best not to encourage a lot of new growth after Spetember, at least here in the land of severe winters.
You'll undoubtedly get answers suggesting organic vs. chemical fertilizers, and I suppose there's value in that. It's just that they are more expensive and usually require lots of mixing. Just depends on how hard you want to work at growing them.
Best of luck this season!