I use 2 drops per gallon with every watering. For transplanting mix as per label then soak bark in it overnight. After plant is situated pour the remaineder through the bark to "water it in". You should not try to use the concentrate directly on the plant. This is a very powerful chemical and 2 drops per gallon is all you need.
I presoak potting medium with about 1/2 tsp/gal when repotting, or if I import some bare-root plants that come in really desiccated and rootless, I soak the plant in that same solution for about an hour, or just add 1 or 2 drops/gal as an additive to fertilizers,.