Most importantly, woody plants shouldn't be fertilized late in the growing season. To avoid this problem, we do not recommend fertilizing woody plants after August 15. Most trees and shrubs are grown for their foliage and structure but there are also some varieties grown for their beautiful flowers. Plants that are grown especially for their flowers need extra phosphorus. Phosphorus encourages blooming as well as strong roots and disease resistance.
Fertilizers come in several forms.
There are also liquid forms that can be injected into the soil or poured on. The fertilizer needs to match both your needs and the needs of the plant. Dry fertilizer is inexpensive. If you are spreading it on the surface, dry fertilizers are easy to apply. If you are drilling it in, it will take more of your time and labor.