The large deep purplish-blue star-shaped flowers open from balloon shaped buds look as though one flower was neatly tucked inside the other. The Double Blue Balloon flower is a clump forming taprooted perennial that produces more and more flowering stems as the plant ages. They begin to flower in about mid summer and continue nearly until fall. Double Blue is a larger growing variety that can reach about 30" high and also produces purple and yellow fall color. It was also one of the top-rated cultivars from the Chicago Botanic Garden's trials receiving 4 out of 4 stars. An easy, low maintenance, and conversation starting perennial for the garden and landscape. Item# 11629