http://www.endlesssummerblooms.com/

Endless Summer Hydrangeas are mop head type Hydrangeas that have the unique ability to bloom on both old and new wood. The result is a plant that flowers all summer long. It is also an unusually hardy Hydrangea macrophylla. The flowers grow up to 8" in diameter, with pink blooms in alkaline soils and blue blooms in acidic soils.