I use the fine, water-solubel granules that are diluted, 1 tablespoon per gallon of water.
Liquid fertilizers can be applied to the soil, or sprayed directly on the rose foilage, where the nutrients will be readily absorbed.
You can also use a convinient hose-end sprayer, which I do a lot.
This fertilizer is especially useful for newly planted roses, container plantings, and roses that need a quick boost.
Apply every week or two during the growing season, for maximum flower production.
Here is the quality liquid fertilizer that I use for my roses. Just order it here for your convinience.