Technical Abstract: Clethra alnifolia, commonly known as clethra, summersweet or sweet pepperbush, is a ornamental shrub native to the eastern U.S. A new C. alnifolia cultivar was released in 2011 by the U.S. National Arboretum. ‘Firefly’ was selected for its yellow to lime-green foliage. It is a second-generation seedling derived from a ‘Compacta’ × ‘Ruby Spice’ hybridization. It has grown to 3 ft tall and 3 ft wide in 5 years. Foliage is yellow when ‘Firefly’ is grown in full sun and lime-green when grown in full shade. In mid-summer, it is covered with white, fragrant, flowers borne on 3 inch panicles. ‘Firefly’ is cold hardy in USDA zones 4 to 8. It performs best when grown in partial shade as foliage may burn in full sun, especially when grown in the warmer areas of its adaptation. Foliage color is not as striking when plants are grown in heavy shade. It is well suited for use as a specimen plant, as a hedge or in mixed borders. Because of its yellow to lime-green foliage, ‘Firefly’ adds interest to shady areas of the garden.