Quickly lowers soil pH. Aluminum Sulphate is recommended for blueberry, blue spruce, dogwood, hydrangea, magnolia and most acid loving plants.

Garden Areas: Apply 50-60 g (3-4 tbsp.) evenly over each square meter (10 sq.ft). May be repeated every 3-4 weeks over the growing season.
Hydrangeas: For blue flowers, mix 15 g (1 tbsp) per 4 L (1 gal) water and apply to dripline once in March, April and May.