The highly recommended boxwood cultivars are:
1. Buxus microphylla ‘Compacta’ – Grown since 1912, it is occasionally misnamed “Kingsville Dwarf from the Kingsville Nursery where this plant was first distributed. Annual growth averages ¼” to ½” which makes it the slowest growing boxwood. The small leaves average ½” long and less than ¼” wide. The plant has a tight low mounding habit and grows best in full shade. Twenty-five-vear-old plants average 10″ in height and 18″ in width. Hardy to Zone 5.
2. Buxus microphylla ‘Grace Hendrick Phillips’ – A handsome, broadly conical, dwarf growing plant with small dark green leaves throughout the year. At 21 years of age it will grow to 23″ tall and 35″ wide. Hardy to Zone 5.
3. Buxus microphylla ‘Green Pillow’ – This plant is similar to ‘Compacta’ except the leaves are about twice as large. The dense and compact habit makes it a good border or edging plant. At 30 years of age this plant can be 30″ high and 40″ wide. Hardy to Zone 5.
4. Buxus microphylla var. japonica ‘Morris Midget’ – A unique, dense boxwood, low mound with a smooth outline. It is very slow growing and at 40 years of age will be only 1 ½’ tall and 3 to 4′ wide. Hardy to Zone 6.
5. Buxus sempervirens ‘Arborescens’ – A very common landscape plant, its large size is best suited as a large hedge or in screen plantings. Specimens can live 175 years. Growth of 20′ tall and 15′ wide is rather typical for a mature 40-year-old plant. Hardy to Zone 5 or 6.
6. Buxus sempervirens ‘Elegantissima’ – The best of the variegated boxwoods, its leaves have a bright, irregular creamy-white margin with a green center. Both the leaves and plant are small in size. The mature size is 7′ tall and 7′ wide. Hardy to Zone 6.
7. Buxus sempervirens ‘Graham Blandy’ – This striking plant has straight sides that form a very narrow, upright plant. Spring growth is occasionally pulled down by spring rains and should be pruned to maintain the parallel sides. A 20-year-old plant will be about 9′ tall and only 1′ – 1 ½’ wide. Mature height is 15′-18′. Probably hardy to Zone 5.
8. Buxus sempervirens ‘Pendula’ – It has a unique J, L, or even K shape. A small plant at 30 years of age will be only 5 ½’ tall and averages about 5′ wide if not permitted to layer. Hardy to Zone 5 or 6.
9. Buxus sempervirens ‘Suffruticosa’ – The most popular and widely grown boxwood, it is usually referred to as English boxwood or true dwarf boxwood. A rounded plant with tufts of growth resembling a cloud, it has small, rounded leaves giving the plant a dense habit. Noted for its slow growth rate, averaging ¾” to 1 ¼” per year. Hardy to Zone 5.
10. Buxus sempervirens ‘Vardar Valley’ – Originated in the Vardar River Valley of Macedonia and was selected for its cold-hardy characteristic. It retains its dark green color throughout the winter. Spring growth has a prominent bluish cast that slowly weathers off by late summer or fall. Hardy to Zone 4.
11. Buxus sinica var. insularis ‘Justin Brouwers’ – A very superior, coldhardy Korean boxwood. Growing in a handsome conical shape, the pointy, dark green leaves make this a dependable plant. Hardy to Zone 4.
12. Buxus ‘Green Mountain’ – The carefree foliage remains dark green throughout the winter. Has a good, dense pyramidal habit. A 10-year-old is 3′ 6″ high and 18″ wide. The mature size is unknown. Hardy to Zone 4.