Welcome to the board. This topic has been kicked around on here many times and ideas vary about what type, but 10-10-10 or other blends are better than nothing. I' ve always thought that the fertilizer blended for pecan groves would have some advantages. Be sure not to apply the fertilizer too late in the spring. I' ve always heard that fertilizing after the blooms have started developing will cause them to cast. Jan or Feb would probably be best.