Apply fertilizer or manure in early spring before growth resumes to encourage maximum growth during the growing season. Fertilizing with nitrogen in late summer or early fall, on the other hand, will stimulate late season growth that is more susceptible to winter injury. Before planting Most garden soils are not suited for growing blueberries and must be modified before planting. Before planting blueberries, a soil test is essential to determine pH and soil nutrient levels. Never add lime to soils where you are going to grow blueberries.
Blueberries prefer nitrogen in an ammonium form over a nitrate form.
Succeeding years Apply fertilizer each year when growth starts or blossoms appear. Apply 2 oz. Increase the amount of ammonium sulfate by 1 ounce per year up to the fifth year. After the fifth year, do not exceed 4 oz. In years when organic mulches are applied, increase the recommended amount by one- half.