ABOUT BOXWOOD / Frequently Asked Questions
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 365 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.
When and where was the the first boxwood planting in America?
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.
What are some boxwood plants recommended for the landscape?
It is a popular myth that there are two kinds of boxwood - Buxus sempervirens (American) and Buxus sempervirens ‘Suffruticosa’ (English). Currently there are approximately 217 registered cultivars and about 148 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’.
How are boxwood plants used in the landscape and where can they be seen?
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. Care should be taken in selecting boxwood that fit the height and shape desired for the location. Back to Top
Seasonal Care. When would I plant, mulch, prune...?
Boxwood is considered to be a low-maintenance shrub, but certain practices are recommended to keep the plants healthy. 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. The fall is the best time for boxwood planting and mulching, while the winter is the ideal time for pruning, thinning, and protection.
Read more from our Boxwood Bulletin archives on Spring Care Fall Care Winter Care
How do I prevent Boxwood Blight?
The American Boxwood Society recently held a seminar on Boxwood blight, Calonectria pseudonaviculata (also known as Cylindrocladium buxicola). Click here to watch videos from the event.
Outside Resources: Boxwood Blight Update by Saunders Brothers. USDA Boxwood Blight Fact Sheet.
Overview - Fighting Disease with Good Boxwood Care
With boxwood blight becoming a major concern for gardeners, keeping our boxwood healthy so it can successfully resist infection is a top priority. Thoughtful care is the answer; knowing what constitutes proper care is vital.
Begin with the right plant for the right place. If yours is an established garden, you may have discovered that errors were made in selecting box cultivars that are much too large for the space they are in. If you are just laying out your garden plan, it is important to know that good care begins with choosing the right boxwood for your space. The right plant can greatly reduce maintenance requirements that put stress on the plant. The ultimate size of a plant is very important-it wants to become what nature has decreed, and trying to hold it back by constant pruning weakens the plant, opens it up to disease and eventually it will succumb. Decide from day one whether your choice will quickly outgrow its allotted space and be dependent on pruning to maintain its optimum size.
Do some research when selecting your plants. Many boxwood cultivars maintain a small size naturally, thereby reducing pruning tasks and the stress they cause. More good news-these cultivars add a great deal of interest to the garden that regularly sheared large cultivars do not add. Consider ‘Morris Midget’ , ‘Justin Brouwers’, or ‘Jensen’, one of the handsomest boxwood plants out there. Reduce the plant size, reduce your pruning chores and reduce the stress placed on the plant-a healthier plant, a happier gardener!
If you prefer the precise sheared lines of boxwood in your garden, know that your maintenance requirements will escalate and so will your chances of producing stressed plants and ultimately diseased plants. It’s an unpleasant fact. But nature does not appreciate manipulation-never has. The inescapable can be postponed by keeping the shearing to a once-a-year procedure and using the thinning method for keeping the plant somewhat contained. Pruning the branches of box such as ‘Green Velvet’ produces branched tips which eventually form a canopy that shuts out light and air-the beginning of an unhealthy plant. It is necessary to cut out or thin the branched tops by cutting down into the plant beyond the branching, opening the plant up. It is a labor intensive procedure. It is important to do a good clean up after pruning. Debris provides a breeding place for fungal diseases.
The excessive clipping of slow-growing boxwood like B. sempervirens ‘Suffruticosa’ (English boxwood) when trying to keep an unrealistically tiny plant, will place the plant under severe stress and it will eventually fall victim to disease and death. Instead of manipulating such a plant, substitute other kinds of plants. If you are after a really petite edging, consider herb plants - thyme, teucrium, santolina; not the same look, but an acceptable and interesting alternative to stressed, pathetic looking ‘Suffruticosa’. A bonus is there, too - delightful fragrance.
Practices other than excessive pruning can cause health problems in boxwood, too. Planted in decent soil to begin with, box is a fairly self-sufficient plant (and left to be just that produces a beautiful sight usually) that needs little or no fertilizer. Over fertilizing will most certainly lead to a confused, stressed plant that will soon decline. Unless you garden on notoriously poor soil or only in pots, your boxwood should not need fertilization. If the gardener cannot resist doing it, a light, organic fertilizer once a year is acceptable. Incidentally, the fertilization of pot-grown plants can be a tricky thing. It must be carefully done in very small amounts with a mild organic fertilizer. Check out your product with care.
Overwatering is another way of dooming boxwood. An excess of water is usually the result of using an automatic irrigation system. These systems are a great help in times of extended dryness, but otherwise are often overused and destroy lots of boxwood. Box like most plants, needs a well-drained situation, something to consider carefully in your original layout work. Constant dampness is to be avoided.
As in fertilizing and water, restraint is the key to proper mulching. Too much will suffocate shallow roots and retain moisture too long. Damp mulch provides the perfect opportunity for fungal diseases. Likewise, do your weeding with care. Overzealous use of sharp tools in weeding can cause damage to the roots of boxwood that provides entry points for disease and injury to the entire plant. To sum up briefly: avoid a regimen of too much care for your boxwood. A program of judicious pruning (thinning) and cleanup, and providing other care only when it seems to be called for, should be the rule for boxwood which was thoughtfully planted in healthy soil to begin with. Ne quid nimis - nothing in excess. When the Romans forgot this, an entire empire collapsed. - The Boxwood Bulletin, Vol 52, No 1. Written by Kelly McGeath
Are boxwood susceptible to other pests and diseases?
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.
Read more from our Boxwood Bulletin archives on Leafminer or click here to watch a video on Leafminer
What new pests should I keep an eye out for?
Box tree moths, a major pest in the UK since 2006, were spotted in Ontario, Canada in August of 2018. Identification and treatment is key in preventing the spread of these pests. The European Boxwood and Topiary Society has a wonderful fact sheet on their website.
How do I know whether I should fertilize my boxwood?
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.
What kind of fertilizer is best and when should I use it?
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.
What is the best method to apply fertilizers?
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.
What does soil pH have to do with fertilizer?
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 6.8 and 7.5. 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. Your County Extension Service is an excellent resource for recommendations for properly adjusting soil pH. A soil test analysis always provides the most reliable guide to determine if the pH or nutrients need to be adjusted, and to the appropriate degree.
- Excerpted from the “BOXWOOD HANDBOOK A Practical Guide to Knowing and Growing Boxwood”. Click here to order.
How are boxwood propagated?
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. Back to Top
How can I learn more about boxwood?
Detailed sourcebooks for boxwood are few. The most highly recommended was 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 email@example.com
The Different Strains of Boxwood Blight
Presented by Margery Daughtrey Cornell Cooperative Extension. Long Island Horticulture Research & Education Center.
Future Regulation of Boxwood Blight
Presented by Jill Calaboro. Science & Research Programs Director at AmericanHort.
Blight Resistant Boxwood Using Genetic Engineering
Presented by Paul Vincelli. Professor of Plant Pathology at the University of Kentucky.
Boxwood Fungicide Management | Cures and Prevention
Presented by Jim LaMondia. Chief Scientist at the Connecticut Agriculture Experiment Station.
Using Mulch to Manage Boxwood Blight
Presented by Chuan Hong. Professor in the Department of Plant Pathology & Weed Science at Virginia Tech.
Mulching Options to Prevent Disease in Boxwood
Presented by Anton Baudoin. Virginia Tech.
Using Boxwood in Public Gardens | Longwood Gardens
Presented by Matt Taylor. Director of Research & Conservation at Longwood Gardens.
70 Years of Love for Boxwood and Family
Presented by Paul Saunders. Owner of Saunders Brothers Wholesale Nursery.
Boxwood Diseases & The Future of Boxwood | Industry Perspectives
Presented by Mark Sellew of Prides Corner; Robert Saunders of Saunders Brothers Inc; and Hugh Crump of Greenline Design.
USDA Boxwood Breeding Research | Boxwood Diseases
Presented by Margaret Pooler. Supervisory Research Geneticist (Plants) at the USDA.
Sanitation Practices for Mitigating Boxwood Blight
Presented by Chuan Hong. Professor in the Department of Plant Pathology & Weed Science at Virginia Tech.
History of Boxwood Blight in Europe
Presented by Didier Hermans. Herplants Nursery in Belgium.
Managing Boxwood Leafminer
Presented by Dan Gilrein. Cornell Cooperative Extension. Long Island Horticulture Research & Education Center.