Bartlett Tree Experts: Boxwood

Buxus sempervirens

Boxwood is one of the most common landscape plants in the world. Genus of about 70 species of evergreen shrubs and trees found in habitats ranging from rocky hills to woodland in Europe, Asia, Africa, and Central America. Boxwood (Buxus sempiverens) is the aristocrat of formal gardens. Dwarf varieties, known as English boxwood are extensively used as edging, hedges, and foundation plants. The larger varieties, known as American boxwood, are used as screens, foundation, and formal plantings

Culture
Concerns
Management

Culture for Boxwood

Boxwood performs best in partial shade, but will tolerate full sun. Soils must be well drained, organic, slightly acid to neutral pH, and fertile. The shallow root system is intolerant of moisture extremes and competition with turf and other ground covers. A light layer of mulch benefits root development. Soil disturbances such as compaction, cultivation, and construction must be avoided in the plant’s vicinity. On exposed sites, boxwood is very sensitive to foliage desiccation especially in winter. Often sheared, but hand pruning will lead to better health and thicker canopy. Often turns yellow to orange in winter when exposed to bright sun under cold conditions.

Concerns about Boxwood

Boxwood is susceptible to a number of pests and disorders. Foliage feeding pests include psyllids, spider mites, and leaf miners. Box blight is a potentially lethal disease. This disease causes characteristic leaf spots, followed by twig canker, defoliation, and plant death. Phytophthora root rot is a leading cause of premature decline and death. Boxwood spider mites, leafminer, and psyllid are all treatable pests that cause foliar damage. Volutella blight is not lethal, but will kill individual branches. Boxwood also is very sensitive to root feeding nematodes. Nematodes can severely stunt root growth and predispose plants to winter injury. Plants stressed by root disease, winter injury, or other factors are prone to canker diseases that cause branch and stem dieback.

Management Practices for Boxwood

Sample soils for nutrient and pH levels especially if deficiency symptoms were evident during the growing season. If plants exhibit decline, sample roots or root collar for Phytophthora root rot. Check for box blight and treat with appropriate fungicide sprays. In areas with heavy boxwood blight pressure, preventatively fungicide applications are recommended. Fertilize annually and apply potassium phosphite to reduce stress during very hot and dry weather.