At first glance, it would appear that we decided to introduce this beautiful mountain hydrangea solely for its waterlily-like double florets. But that's only part of the story - this is also one of the most prolific reblooming hydrangeas we've ever seen. All summer long, it devotes its energies to creating flower buds on its new growth so that you have a constant supply of fabulous blooms from early summer through frost. Tuff Stuff Ah-Ha® hydrangea will bloom pink or blue, depending on soil chemistry. Pink blooms will turn blue with the right ph level of 4.5 to 5.0 which means simply adding aluminum sulfate.