IN THE GARDEN

boxwood

An important centerpiece of the living collection at the Dixon Gallery & Gardens is the boxwood. At first glance, these medium to dark green shrubs with inconspicuous flowers might seem boring to serious gardeners. I have grown to appreciate boxwood, however, thanks to their incredible diversity in shape, size and texture.

TEXT BY DALE SKAGGS, DIRECTOR OF HORTICULTURE AT DIXON GALLERY & GARDENS

boxwood are fairly easy to maintain. In fact, these plants can be kept in good shape with very little pruning if the right cultivar is chosen for a particular spot. Minding the garden adage “right plant, right place” will ensure the health of the boxwood, allowing it to grow to its specific height, shape and beauty. Commercial landscapers often trim the plants with gas-powered shears, without any regard for the natural form of the particular cultivar.

Historically the oldest cultivated ornamental plant, boxwood are long lived, sometimes surviving for centuries. These evergreens, mostly slow-growing, can make up the bones of the garden, providing year-round structure that will stand the test of time.

The most commonly planted variety is the so-called American boxwood (Buxus sempervirens). It is not from America but was simply a favorite of the early colonists, hence the common name. The American boxwood has a reputation for being tricky to grow in the Mid South, as our poorly drained, acidic soils and high humidity are not optimal for its success. The English box, the true Buxus sempervirens, is even more susceptible to local soil and weather conditions and will not work for us in Memphis. I have seen it fail many, many times.

However, some boxwood cultivars do exceedingly well here. I have written several articles in the past covering the best choices for our climate and conditions, but I have had to alter my list recently due to cases of boxwood blight in Memphis. Boxwood blight has been present in other parts of the country, such as Virginia and North Carolina, for almost a decade. Countries in Europe have been dealing with the disease even longer.

On Feb. 18 from 9 a.m. until 4 p.m., the Dixon will host a full-day boxwood seminar to discuss this beloved plant and its culture. Admission is free and the event is open to the gardening public. National and local experts and industry professionals will discuss boxwood blight and best practices for dealing with this threat.

the sad news is that when conditions are right, this pathogen can spread quickly and defoliate an entire garden practically overnight. There is no real cure but you can take preventative measures to help deal with this horrible pest.

Boxwood blight is caused by the pathogen Calonectria pseudonaviculata, which will also affect other shade-loving plants like sweet box and pachysandra. A tissue test performed at a diagnostic clinic for plant diseases can confirm boxwood blight.

Boxwood blight is spread by contact with infected plants from nurseries, or by contact with contaminated tools, clothing or boxwood used in holiday decorations. Keeping it out of your garden is the best way to deal with the pest, so sanitize any tools that you use at other locations with a 1:9 bleach to water solution.

Spores can persist in the soil for up to five years, so even a new boxwood planted where an infected plant was removed can become diseased. There is no cure, but the condition can be treated by spraying a chlorothalonil-containing fungicide every seven to 14 days during the growing season when temperatures are above 60˚F, or by removing affected plants.

The Dixon has a historic relationship with boxwood, and I find them to be such useful plants in the garden that I’m not ready to abandon their use any time soon. The good news is that some varieties of boxwood seem to have a natural genetic resistance to the blight, so gardeners are planting these cultivars, and breeders are working to use the resistant varieties in the creation of newer cultivars.