Boxwood Basics

Mature boxwoods and an attractive gate give an old Accomack Co. garden a sense of time and place.

     The most familiar species of boxwood is Buxus sempervirens which is referred to as common or American boxwood (though it is not American in origin, rather it is from the Mediterranean).  This plant has rich dark green foliage and a fairly dense and rounded habit.  Although it grows slowly, common boxwood can reach 15 to 20' (or more) tall and wide if it is never pruned.  This fall I travelled to the Barboursville Ruins in Orange Co., Virginia where boxwoods surround the Jefferson designed house.  The boxwoods there are almost 3 stories tall and I was able to walk under them without hitting my head.  A much shorter variety is B. sempervirens 'Suffruticosa', best known as old English boxwood.  This dense, compact variety rarely gets more than 3-4' tall and wide, and it has a much lighter, more olive-green color.  Old English is the variety most often used for edging and in knot gardens.  Another variety of common boxwood is 'Dee Runk', which is valued for its unusual narrow growth habit.  It reaches about 12' tall, but only gets 2.5' wide, making it ideal for accent plantings.  'Elegantissima' is a variegated form that with age can reach 5-8' tall and wide, but what really stands out to me is the cream and green variegated foliage, perfect for containers around the winter holidays.

Giant boxwoods surround the Barboursville Ruins in Orange Co., Virginia

     All varieties of common Boxwood have a few particular cultural requirements.  In this area it is important that they do not get a lot of afternoon sun, filtered light is preferred.  You will want to also make sure that the area where they are planted has good drainage.  Heavy, mucky wet soils will be death to boxwood, as will salt water.  Their root system is fairly broad but shallow, so try not to disturb them when you are planting nearby.  Since they are shallow rooted, make sure they are also mulched well to retain moisture, and be prepared to provide extra water during droughts.  Boxwoods prefer soil that is neutral to slightly alkaline, so in Tidewater's acidic soils you may need to add some lime to raise the pH.  If they are planted in an area that is particularly exposed and windy during the winter, you will see discoloration of the foliage.  There are also several diseases and insects that can be a problem.  Leaf miners and spider mites can be an issue, though if you are diligent they are easily treated at the first sign of infestation.  Most of their diseases can be prevented by proper soil conditioning and by providing good air circulation, but occasionally you may have to reach for a chemical control.

Colonial Williamsburg is a great place to see how versitile boxwood can be.

     After reading the previous paragraph some of you may think twice about growing boxwood.  However, there are other varieties not as particular about soil, location or as disease prone.  Littleleaf boxwood (Buxus microphylla) is a variety of Asian boxwood from which many cultivars and hybrids have been developed.  Most of these are smaller, looser, lighter in color and generally more tolerant of less than ideal conditions.  Japanese boxwood (B. microphylla var. japonica) can grow 3-6' tall and is particularly well-adapted to our climate.  'Wintergreen' is perhaps the most common of the Asian varieties, and this one is more compact reaching only 3-4' tall and wide.  Visitors to the garden center may have noticed several plantings of the very tight and short 'Kingsville Dwarf', which we have planted around the gardens.  This one is also great for bonsai as they can easily be shaped to look like miniature trees.  One issue many gardeners have with the Asian varieties is that they do not look like traditional Boxwood.  However, there are several newer hybrids that have the look of common boxwood, but with the constitution of the sturdier Asians.  'Green Velvet' is one of these that we really like, in fact it was picked to be a Plant of Distinction with the Beautiful Gardens® program.

Boxwoods flank Stratford Hall, the Lee family ancestoral home.

    

     Though they are more tolerant of adversity, the same general care guidelines apply to the Asian varieties as do to the common boxwood.  The pruning recommendations are the same for all types of boxwood.  They should receive a regular thinning, preferably in the late winter, just before spring growth occurs.  When you thin boxwood you are actually removing small sections of branches in such a way as to open up spaces for light and air to penetrate the interior of the plant.  Shearing is the practice of trimming the outside layer of the plant all at the same point.  This produces a lot of thick growth and makes the boxwood look dense and full.  However, if it is done without a regular thinning, the interior of the plant will be barren and leafless.  Occasionally Boxwoods get overgrown or are damaged in such a way that you might consider replacement.  When this occurs you might opt instead to cut the plant just above ground level and allow it to regrow into a nearly new plant.  This type of severe restoration is best done in late winter.

Les Parks