Dogwood trees have fairly shallow roots and can easily be damaged with excess fertilizer. I would suggest using either organic fertilizer or slow release fertilizer when it is time to fertilize the tree. Also, I might suggest that you consider a kousa dogwood for some future planting. They are resistant to the blight that affects the American native dogwoods. I am gradually diversifying the many dogwood trees in my yard. Originally we had about a dozen American dogwoods in the yard. Recently I've planted about four new American dogwoods but also included three kousa dogwoods in the mix. This year has been particularly bad for blight with the young native dogwood trees suffering, but the kousa's are very healthy and show no signs of the problem.