Boxwood Shrubs – varieties & characteristics
There are four basic varieties of boxwoods:
English boxwood, B. sempervirens ‘Suffruticosa,’ is the most commonly grown cultivar, and it was first cultivated in the early 1700’s in the United States. It can reach 3 feet in height and usually grows about 1 inch per year.
English boxwood is rounded, and the overall shape of the plant is similar to a cloud. English boxwood is an evergreen and blooms during the spring.
American boxwood, also known as common boxwood, is a small tree that grows to 10 feet in height, although some older plants can grow up to 20 feet.
American boxwood is an evergreen, slight blooms in spring and is very tolerant of cold weather, making it a good choice for cooler, northern regions. The leaves are waxy and dark green in color, with pale undersides.
Korean boxwood is a variety that grows in an open habit, as opposed to the dense foliage common in other species of boxwood. This increases the circulation and the amount of light that reaches the inner portions of the plant, making it more disease resistant. It is winter hardy, but during periods of extremely low temperatures, the leaves may brown. However, in the spring the green will return and the plant will resume growth as usual.
Korean boxwood forms oval-shaped leaves that usually only grow to about ½ inch in length. The spring flowers are small and green or yellow in color. Korean boxwood grows to about 4 feet in height.
Japanese boxwood was first grown in the United States in 1890 and is considered one of the most adaptable species of boxwood available. It can grow up to 8 feet in height with a spread of about 6 feet if grown in the proper environment.
Japanese Boxwood foliage is dark green and grows to about 1 inch in length. It is evergreen, though in cooler climates the leaves may adopt a yellow or brown tinge. Commonly grown as a low hedge; it forms an excellent border when maintained. The flowers bloom in April, but are not showy.
Here are specific boxwoods with characteristics:
Small-Leaved Boxwood ~ (Buxus microphylla)
- Grace Hendrick Phillips: very dwarf; 1 × 2 foot; zones 6–8
- Compacta (Kingsville Dwarf): the smallest of them all, tiny leaves, dense, very slow; 1 × 1.5 foot; zones 6–8
Japanese Boxwood ~ (Buxus microphylla var. japonica )
- Green Beauty: deep green, responds well to pruning, a good substitute for English box; 3 × 3 feet; zones 6–8
- Morris Dwarf: slow, formal hedge for sun; 1 × 1 foot; zones 6–8
- Morris Midget: very dwarf, small leaves, sun tolerant; 1 x 1 foot; zones 6–8
Common or American Boxwood ~ (Buxus sempervirens)
- B. sempervirens: called American boxwood, tall, tried and true species; 5 × 4 feet; zones 5–8
- Dee Runk: upright fast growth; 8 x 2 feet; zones 6–8
- Elegantissima: best variegated gray-green and cream, disease-resistant; 3 × 2.5 feet; zones 6–8
- Fastigiata: bluish-green upright growth for hedge; 8 × 3 feet; zones 6–8
- Graham Blandy: most narrow columnar, better in cold climates, may need tying or pruning; 7 × 1 feet; zones 5–6
- Jensen: similar to English; 2 × 2 feet; zones 6–8
- Newport Blue: globular, quite blue-green foliage; 4 × 3 feet; zones 6–8
- Pyramidalis: upright cone; 8 × 4 feet; zones 6–8
- Rotundifolia: fast growing, largest leaves, shade tolerant; 5 × 4 feet; zone 6
- Vardar Valley: disease-resistant, bluish new growth, hardy; 1 × 3 feet; zones 5–8
- Wanford Page: long-lasting chartreuse new growth then leaves mottled green and yellow, dwarf; 2 × 1.5 feet; zones 6–8
Korean Boxwood ~ (Buxus sinica var. insularis)
- Justin Brouwers: sun to shade, natural globe; 2 × 2 feet; zones 6–8
- Nana: spreading dwarf with narrow leaves, chartreuse in spring, slow; 1 × 3 feet; zones 6–8
- Wintergreen: cold-hardy, good for hedge, fast-growing; 4 × 4 feet; zones 5–8
Hybrid Boxwood ~ (Buxus hybrids)
- Glencoe: selected at Chicago Botanic Garden, container plant, edging, hardy; 4 × 5 feet; zones 4–8
- Green Mound: sun to shade, globular, hardy; 2 × 2 feet; zones 4–8
- Green Mountain: upright, conical, hardy; 4 × 3 feet; zones 4–8
- Green Velvet: lime green spring growth, mounding, hardy, 2 × 2.5 feet; zones 4–8