Chinese Holy Shrubs Not Growing?

I have had these in the garden going on 2 years. Why aren't these plants growing rapidly? I have yet to notice any growth! I have been feeding them Miracle Gro liquid plant food, but still not much growth in height or width.

I want to know what I need to do differently? 2 years is a long time, and there should be some noticeable growth going on, but this is not the case, why?

By Bertha L.