This method is the most effective in a bed without ground cover or grass. Fertilizer may be applied below the soil surface, at and beyond the drip line, using a root feeder with a fertilizer attachment. Although this method requires the most work, it produces the best results. For general fertilizing, use a complete fertilizer that has the approximate ratio of three parts nitrogen, one part phosphorus and one part potassium and does not contain herbicides. For iron deficiencies use a chelated iron fertilizer.
Chelates help keep iron from binding to soil particles for a period of time.
Fertilize before July or after the leaves have dropped in the fall so the plant is able to harden-off properly for the fall. Over-fertilizing can severely damage or kill woody plants. Read manufacturer's instructions on the amount of fertilizer to use before beginning. Permission is hereby given to duplicate this Plant talk Colorado TM script as is if credit is given to the sources.