Boxwood has been described as "Man's Oldest Garden Ornament". It was introduced to North America from Europe in the 17th century and has been an important part of many American gardens ever since. This elegant and long-lived evergreen shrub with its small leaves and fine texture has many different uses in the landscape. It is commonly used in formal hedges, as an edging plant, in foundation plantings, and even as an impressive accent plant. Boxwoods are also one of the best shrubs for use in creating magnificent topiaries.
Although there are more than 150 different boxwood cultivars, two types, American Boxwood (Buxus sempervirens) and English boxwood (Buxus sempervirens 'Suffruticosa'), are the most commonly grown in American gardens. English boxwood is considered the "True Edging" Boxwood and this low-growing form is often used in more formal landscape designs. Buxus sempervirens also includes many of the taller cultivars that are seen around some of the older homes especially in the Mid-Atlantic region. Newer cultivars have been selected for a variety of different growth forms and also for increased winter hardiness. Buxus microphylla (Littleleaf boxwood) is a lower growing species that includes the very slow growing Japanese boxwood which grows from 3 to 6 feet tall. This species also includes the smallest cultivar, 'Compacta' which grows only to about 12" tall!
Boxwood is considered a fairly low-maintenance shrub. Most cultivars prefer full sun or part shade, however, in colder regions, they perform better if they are planted in a less exposed area where they are protected from winter winds and full sun exposure. Spraying with an anti-desiccant like Bonide Wilt Stop in the late fall and again in mid-winter can help prevent winter burn and sun scald.
Well-drained soil is essential to avoid problems with root rot. If you are planting in heavy clay soil, add gypsum or Espoma Soil Perfector and good organic matter to improve drainage. Be very careful if you have an automatic sprinkling system as this often keeps the soil too wet for boxwood.
At planting time, amend the soil with an organic fertilizer like Plant-tone or Holly-tone, rock phosphate, and green sand according to the Viette recommendations. After the first year, fertilize with Plant-tone or Holly-tone in the early spring and again in the fall. Avoid fertilizing with chemical or quick release fertilizers late in the summer or fall as this can lead to a burst of tender new growth that will be subject to winter injury.
Pruning of boxwoods is done mainly to control size and shape, and to improve the health of the shrub. Annual thinning with hand shears is recognized as one of the best pruning methods for maintaining the health of the shrub. Happily, you can do this type of thinning in early winter when the trimmings can be used for holiday decorating!
Boxwood is one of the best of the broadleaf evergreens to use for holiday decorating because the leaves hold their rich green color well and remain fresh for a long time. In outside arrangements, the cool temperatures keep them fresh even without water! To cut boxwood greens for decorating, follow the procedures outlined below for annual thinning.
Annual thinning with hand shears is recommended to open up the plant and bring air, light, and water to the interior of the shrub. This type of pruning not only reduces the incidence of disease by increasing air circulation, it also rejuvenates the plant by stimulating the production of basal buds and new interior growth.
Shearing boxwood is not recommended because it stimulates growth only at the ends of the branches. Continual shearing causes the exterior of the shrub to become very dense and reduces the amount of light and air that reaches the interior of the shrub. This growth pattern is unhealthy for the plant as a whole because the lack of light and air circulation causes inner leaves to die and can also lead to an increase in disease. If you do shear your boxwood, be sure to also do some thinning afterwards to keep it from becoming too dense.
Severe pruning of overgrown boxwood should only be done in late winter or early spring when the boxwood is dormant. They can be pruned heavily until just bare branches remain or you can even cut them back to one to two feet above the ground. The boxwood in this photo taken in early April of 2009 had been cut back to about 15" from the ground in March of 2007. This type of severe pruning is not always 100% successful but a very high percentage do come back with beautiful new growth!
After severe pruning, fertilize your shrubs with Plant-tone, rock phosphate, and green sand according to the Viette's recommendations.