Good morning & welcome!
I have never fertilized a shrub, just put compost around the base occasionally, to keep a "mulched" layer of it. Fertilizer of the packaged, synthetic variety is a relatively new invention, not at all necessary when growing in healthy soil.
The best thing one can do for any plants in the ground is to improve the soil by adding organic matter to the surface:
http://permaculturenews.org/20...
