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.
Wee Bit Grumpy® Hydrangea
Hydrangea macrophylla 'Stragrum'
Wee Bit Grumpy is a good small-sized hydrangea for the shade garden, reaching two to three feet tall and wide--perfect for fitting under windows or in front of taller trees and shrubs. It produces loads of large flowers--blooming blue in acidic soil or pink in alkaline soil. And it blooms on both old and new wood to keep the show going all season. Using Aluminum Sulfate in early spring will help all hydrangeas produce blue flowers instead of pink flowers.