
Most garden centers sell fertilizers that have designed to feed a specific group of plants. You can find fertilizers for roses, fertilizers for holly plants, and fertilizers for azaleas among others. If you have these plants, then you can be confident that if you use these plant specific fertilizers, your plant is getting just the right mixture of major and minor elements to keep that plant healthy and happy.
At the same time, most of the plants for which there are plant specific fertilizer products will do fine being fed with general purpose fertilzers.