Hi Jack, the best advice is to follow the dosing instructions on the package of any plant food but I know with plants in the ground this can be hard to figure. I suggest one tablespoon around the base of each boxwood. Sprinkle evenly and work the product into the top half inch of soil them move on to the next boxwood making a circle around each plant. You can replace the mulch after you fertilize. The Japanese yews are large plants and they can handle 4 oz of Osmocote sprinkled around the base of each yew. Again, apply in a circle around the drip line of the shrub and work it gently into the top half inch of soil. It is pretty hard to overfeed with Osmocote in one application if you are feeding trees and shrubs but it can happen especially in warm weather when the product is released more quickly into the soil. Keep growing, Marianne Binetti