First, you may not need to fertilize trees and shrubs after the first few summers - especially if you are using wood chips as a mulch, and the trees and shrubs are showing signs of healthy new growth. Blooming plants, vegetables, groundcovers and young plants require more nutrients than established trees and shrubs and so these are the plants that need additional plant food every spring. I suggest you place the Osmocote near the drip irrigation in late spring as the product needs moisture and warmth to release the nutrients. This will also be a good time to check your irrigation emitters to see that they are not blocked. You should rake aside the stone mulch and the wood chips so the fertilizer is in contact with the soil, but you can then replace the mulch on top of the osmocote so it will continue to block weeds and seal in moisture. Keep growing, Marianne Binetti