Boxwood, "Man's Oldest Garden Ornamental," was introduced to North America from Europe in the mid-1600s and reached its peak popularity in the United States during the early 19th century and again during the Colonial Revival era. Horticultural interest in the genus Buxus is maintained today by many nurserymen, landscapers and homeowners.
While the most familiar forms are what are commonly referred to as "American" (Buxus sempervirens) and "English" (Buxus sempervirens 'Suffruticosa') boxwood, there are about 90 species and over 150 different cultivars known exhibiting a wide variety of forms and foliage. Several of the more unusual cultivars are now in commercial production. Further information about proper cultivation, cultivars suitable for landscape applications, and suppliers of boxwood is available in several ABS publications.
Frequently Asked Questions
How do I thin my boxwood?(a link to National Arboretum)
The first planting occurred about 1653 at Sylvester Manor on Shelter Island, the NW part of Long Island in New York, using boxwood brought over the Atlantic Ocean from Amsterdam.
It is a popular myth that there are two kinds of boxwood - Buxus sempervirens (American) and Buxus sempervirens ‘Suffruticosa’ (English). Currently there are approximately 160 registered cultivars and about 115 different cultivars and species that can be obtained commercially. Different boxwood plants and species vary tremendously in size, shape, leaf characteristics, growth rates, and hardiness. Among the many commercially available boxwood, the following are most frequently found (in no specific order): B. harlandii, B. microphylla ‘Compacta’, B. microphylla var. japonica, B. sempervirens ‘Elegantissima’, B. sempervirens ‘Graham Blandy’, B. sempervirens ‘Suffruticosa’, B. sempervirens ‘Vardar Valley’, B. sinica var. insularis ‘Justin Brouwers’, B. sinica var. insularis ‘Winter Beauty’, B. sinica var. insularis ‘Wintergreen’, and Buxus ‘Green Mountain’.
Boxwood plants may be used as individual specimens, hedges, parterres and groups. Special uses include growth in containers, topiary, and bonsai. Boxwood can be seen growing in many public and private gardens in the United States, but most especially in the Mid-Atlantic area. The largest collections of species and cultivars can be seen at the Virginia State Arboretum in Boyce, Virginia, where the American Boxwood Society maintains the Boxwood Memorial Garden and at the U. S. National Arboretum in Washington, D. C.
Boxwood is considered to be a low-maintenance shrub, but certain practices are recommended to keep the plants healthy. The fall is the best time for boxwood planting and mulching, while the winter is the ideal time for pruning, thinning, and protection. Boxwood can be planted in the spring, which is also the time for monitoring insects. Inspection of plants for insects should continue in the summer, during which time there should be attention to weed control and the watering needs of the plants.
By far the most widely used method is stem cuttings, which will produce plants identical to the parent plants. Cuttings, best taken from parent plants from July to December, should be removed from one year old branchlets and placed into containers filled with one of several appropriate media mixes. With frequent watering, rooting usually takes place in two to three months. Boxwood can also be grown by layering, in which roots develop on a stem of a parent plant. Finally, plants can be grown from seedlings, but they can be somewhat variable from the parent plant. (Click here for additional details)
The various pests and diseases that may affect boxwood vary to some extent according to specific plant species and cultivars. Common pests include leafminer, mites, and psyllid. Each of these should be controlled if infestation is severe or intolerable. Although nematodes and several types of fungi may infect boxwood, they are not usually major threats. Boxwood decline, presumably due to the fungus Paecilomyces buxi, is limited to B. sempervirens ‘’Suffruticosa’, and is not a serious problem as it was several decades ago. It should be emphasized that deer will typically not eat boxwood, as the plant reportedly contains a toxic alkaloid.
There is no regular schedule to guide fertilization of boxwood. The most reliable guide to applying fertilizer is by testing the soil. Soil samples analysis by the Cooperative Extension Service will provide appropriate fertilizer recommendations for a specific site.If the boxwood begins to show symptoms of nitrogen deficiency, then it may be time to fertilize. The earliest symptom of nitrogen deficiency is yellowing of lower leaves. It will have a rather uniform yellowing, that is more pronounced on the older leaves inside the plant. The leaves then become smaller and thinner and turn quite bronze in winter. Boxwood leaves will normally stay on the plant for three years. If they fall off earlier, this may be a symptom of nitrogen deficiency.
Granular, urea fertilizer with a 10-6-4, or similar, analysis will be appropriate in most situations. Late fall applications of fertilizer promote root growth and provide best results.
Broadcast fertilizer around the base of the plant - just beyond the drip line. Surface application is the easiest and fastest technique. It is effective around the drip line because the most active roots are located there. Fertilizer particles that come into direct contact with the roots of unmulched boxwood can cause root bum. If the fertilizer is over applied, this will cause the foliage to brown and may even result in branches dying. This can be avoided by broadcasting fertilizers only on mulched boxwood when the soil has adequate moisture.Deep root fertilization, drilling holes and filling them partially with fertilizer, is not recommended. While it does eliminate volatilization of urea and ammonium it is not worth the effort. The roots of boxwood grow close to the surface and they do not benefit from deep root fertilization.
The pH needs to be in a proper range in order for the nutrients to be available to the plant. The optimum soil pH for boxwood is between 6.5 and 7.2. If the pH is below the recommended range, add dolomitic lime. This lime has low oxide content and will persist in the soil for 4‑7 years depending on application rates and soil type. If the pH is above 7.5, then lowering the pH would be in order. This is accomplished by adding iron sulfate. Your County Extension Service is an excellent resource for recommendations for properly adjusting soil pH. A soil test probably will be needed.
Detailed sourcebooks for boxwood are few. The most highly recommended is Boxwood Handbook: A practical guide to knowing and growing boxwood. The author, Lynn R. Batdorf, is the curator of the National Boxwood Collection at the U. S. National Arboretum in Washington, D.C. and is the ABS Registrar for the International Cultivar Registration Authority for Buxus L. Click here to order.
Have further questions? Email the American Boxwood Society at firstname.lastname@example.org