Firestorm’ was hybridized by Dr. Gustav Mehlquist of the University of Connecticut using Rhododendron ‘Vulcan’ as the seed parent and Rhododendron ‘Chocolate Soldier’ as the pollen parent. Its flowers are openly funnel-shaped with wavy edges, 3¼” wide, and are an unmarked bright deep red. The new leaves are lime green and darken as they mature. ‘Firestorm’ is a dense spreading shrub that grows 3 to 4 ft. tall and wide.