Plant of the month series June 2018 for Boulder Colorado landscapes JUNE: BLUE MUFFIN VIBURNUM Viburnum dentatum Blue Muffin is a compact form of Arrowood Viburnum. It has serrated leaves and rich, creamy white flowers in flat topped clusters in mid May through June. Flowers fall and are replaced by vibrant blue berries which birds … More Blue Muffin Viburnum is June Plant of the Month