Summer Snowflake Viburnum is widely loved for its unique tiered branching and its tendency to bloom far longer than other viburnums. It produces large, flat-topped flower clusters (lacecaps). The most striking feature is the repeat blooming—while the heaviest flush is in May, it continues to produce white flowers sporadically throughout the summer and into autumn. The leaves are dark green, deeply veined, and turn a rich reddish-bronze or purple in the fall.