Simplify fertilzation
Garden stores and departments offer numerous brands and types of fertilizers. Gardeners have been trained to think that each type of plant needs its own fertilizer.
Since our soils contain a significant amount of phosphorus and potassium, I have found that lawn fertilizers, which are high in nitrogen, work very well for most trees, shrubs and flowers. The only things I use any other fertilizers for are containers and fruiting vegetables, especially tomatoes.
General purpose fertilizers with a 1-1-1 balance of nitrogen, phosphorus and potassium, or vegetable fertilizers with a 1-2-1 balance are better for fruiting vegetables. Typical offerings are 16-16-16 or 5-10-5. For containers I use a coated fertilizer such as Osmocote, which releases gradually every time plants are watered.
Lawn fertilizers with part of the nitrogen in a slow release form are best for spring application. They will last much longer into the summer. Check the guaranteed analysis label for slowly available nitrogen.
I also like to see micro-nutrients such as iron and zinc included in mixed fertilizers. Organic fertilizers naturally contain all the micro-nutrient elements.