Jack's Classic Hydrangea Blue Fertilizer (7-3-3)
JR Peters Inc. Jack’s Classic Hydrangea Blue is a water soluble fertilizer that is derived from ammonium sulfate and aluminum sulfate. It has an NPK ratio of 7-3-3 and is designed to boost foliage and blooming. In particular, it will enhance blue blooms in your hydrangeas and works great in both pink and blue hydrangea varieties. And while it enhances plant health in white hydrangeas, it will not change the color of white blooms. Follow directions on package and use during the growing season.