Plant width is often difficult to determine because of naturally occurring layering. Japanese boxwood and most of its cultivars are heat tolerant. Buxus microphylla 'Compacta' is hardy to USDA Zone 5. Common or American boxwood, Buxus sempervirens, L. is hardy to USDA Zone 5. This boxwood is a wide-spreading shrub or small tree with very dense evergreen foliage.
Leaves are usually shiny, dark green on the upper surface and pale green on the lower surface.
Flowers, borne in early spring, are pale green. They commonly grow 5 to 10 ft tall. Old plants may attain a height of 20 ft. This species and most of its cultivars are tolerant of cold weather. They are well suited for the piedmont and mountain areas of North Carolina.