Keywords: Nikko Petals 1.jpg Personal photo of 'Nikko Blue' hydrangea petals from my garden in Traverse City Michigan Petal color was altered through regular use of aluminum sulfate pine bark mulch and watering with tap water acidified through the addition of sulfuric acid 2005-09-14 own assumed Shmoopy~commonswiki Ornamental plants Hydrangea macrophylla cultivars |