True garden aristocrats, boxwoods may well be the world's oldest cultivated ornamental plants: They were grown as hedges in ancient Egypt and decorated the gardens of wealthy Romans during the reign of Caesar Augustus. Today, thanks to a wide variety of shapes and sizes, the popularity of boxwoods is rising. They are still widely used as hedges, in formal foundation plantings, and as edgings for walkways and planting beds. In many areas, boxwood is the primary plant in landscapes due to its resistance to damage by deer.
These evergreen shrubs have small (just 14- to 1-in.), lance-shaped to roundish leaves. All are easy to grow where they are adapted, provided they receive good drainage and a modicum of care. If they're grown in loose, fertile soil that contains plenty of organic matter, heavy fertilizing is seldom necessary. Many of the more recent introductions tolerate pruning well, though most boxwoods have a naturally billowing form that requires little or no pruning. Susceptibility to nematodes limits the use of boxwoods in Florida.
B. Green Series. Zones US, MS, LS, CS; USDA 6-9. Group of Canadian hybrids derived from B. microphylla koreana and B. sempervirens. Hardy to between 2F and 30F. All feature handsome, rich green foliage and a naturally attractive shape; need very little pruning. Slight winter bronzing may occur when these are planted in a sunny, southwest-facing location.
'Green Gem'. Slowly forms a mound 23 ft. high and wide. Some bronzing of foliage in winter cold.
'Green Mountain'. Forms a dense, rounded cone to 45 ft. high, 3 ft. wide. Developed as an alternative to dwarf Alberta spruce (Picea glauca 'Conica').
'Green Velvet'. Rounded habit to 23 ft. tall and 3 ft. wide. Very popular and widely used.
B. microphylla. LITTLELEAF BOXWOOD. Zones US, MS, LS, CS; USDA 6-9. Hardy to 10F. Slow-growing species from Japan reaches 34 ft. tall and wide. The plain species is rarely planted; the following varieties and selections are much more common.
'Grace Hendrick Phillips'. A wide, mounding plant that matures at 12 ft. high and 23 ft. wide. Useful as small specimen, foundation plant, or low hedge.
B. m. japonica. JAPANESE BOXWOOD. Zones US, MS, LS, CS; USDA 6-9. Faster growing and taller than the species, to 6 ft. tall and wide. Well suited to the Coastal South; tolerates heat, humidity, and nematodes better than most boxwoods. Round-tipped leaves, 131 in. long. Foliage may take on a bronzy cast in cold winters. Often used as a clipped hedge in Gulf Coast areas. 'Green Beauty' is a rounded form that matures at 4 ft. tall and wide. Foliage is glossy, deep green and holds its color well through the winter. Responds well to pruning and sunny locations. 'Morris Dwarf' is slow growing and compact (12 ft. tall and 2 ft. wide); good for knot gardens and parterres. 'Winter Gem' retains its deep green foliage color through winter.
B. m. koreana. See B. sinica insularis
B. sempervirens. COMMON BOXWOOD, AMERICAN BOXWOOD. Zones US, MS, LS; USDA 6-8. Native to southern Europe, North Africa, western Asia. Hardy to 10F. Densely foliaged shrub is virtually indispensable in formal garden settings. Takes many years to reach 1012 ft. tall and wide. Dark green, oval leaves. Can be used in foundation plantings, for hedges, or pruned into a small tree.
'Aureovariegata' Grows 810 ft. tall and wide, with leaves edged in creamy yellow.
'Dee Runk'. Slender pyramidal plant that grows 810 ft. tall and just 3 ft. wide. Good accent plant or narrow hedge.
'Suffruticosa'. ENGLISH BOXWOOD. Dense, compact, very slow growing; takes many years to reach 3 ft. Often used in formal garden settings. Extensively planted but being replaced by newer selections with greater disease resistance.
'Vardar Valley'. Becomes a flat-topped mound, 23 ft. tall, nearly twice as wide. New spring foliage is a beautiful powder-blue, shading with maturity to dark blue-green. Hardy to about 15F.
'Variegata'. Dense and mounded form, eventually to about 5 ft. tall and wide. Leaves are bright green, edged in white.
B. sinica insularis (B. m. koreana). KOREAN BOXWOOD. Zones US, MS, LS, CS; USDA 6-9. Slower growing and lower than B. m. japonica. Hardy to 25F. Good choice for severe winters of the Upper South. 'Justin Brouwers' grows to 23 ft. tall and wide and is widely used as a replacement for English boxwood (B. sempervirens 'Suffruticosa'). It responds well to pruning into a small hedge or can be left unpruned for a naturally billowing shape.