Shade hydrangeas prefer moist soil and regular watering during the growing season. For most, in order to obtain the blue flower color, apply 2 tablespoons of aluminum sulfate near the base of the plant. A rusty nail or coffee grounds will also increase the acidity of the soil which makes the flowers turn blue.
Nikko Blue Hydrangea
Hydrangea macrophylla 'Nikko Blue'
Nikko Blue is very blue in acidic soils. Aluminum Sulfate will improve acidity of soil for all hydrangeas. Full Description coming soon...