Oct 10, Blueberry plants will not use nitrate fertilizers. Use ammoniacal sources of nitrogen (N) like ammonia sulfate, ammonia nitrate, or urea, and avoid chlorinated compounds like muriate of potash (KCl) and magnesium chloride (MgCl2).
Blueberries do not fertilize the first year. During the following years, fertilize with ammonium sulfate or a complete fertilizer (for acid loving plants) in spring. Split the dose, one as buds open and the second a month later. Sep 02, Avoid fertilizing a blueberry bush with fertilizers that contain a nitrate form of nitrogen as this will damage roots.