Boxwood is one of the
most popular evergreen shrubs. It is easily grown in different soil types as
well as sun or shade. They are very dense and lends itself well to hedges
and accent plantings. Please read our tip sheet for planting
Trees & Shrubs
for planting information.
Insects called psyllids
will cause cupping of the new growth and can be controlled by spraying with
a Bonide Systemic Insect Control spray inmid-May and repeating in 10 days.
Annual thinning brings light and air into the interior of the plant and
encourages the growth of new foliage within the canopy that can take air
into the interior of the plant and encourages the growth of new foliage
within the canopy that can take over for branches damaged by ice or snow.
The best time to thin
Boxwood is early winter, and the branches that are removed make great
Boxwood keeps its
foliage for three years. The current year’s growth almost completely covers
the leaves that grew in the previous two seasons. If you carefully bend the
branches back (pictured, right), you can see that the foliage is growing
only on the outermost reaches of the branches. This severely reduces air
circulation and favors the development of the disease.
To thin Boxwood, use a
bypass pruner that is sharp. Reach inside the shrub about six inches and
prune off the stem. Continue thinning until the small interior twigs just
start to become visible. You should remove about ten percent of the outer
After proper thinning,
small voids appear in the canopy that permit air and sunlight to enter the
interior portions of the shrub. Older leaves are now visible. After two or
three years of annual thinning, new growth will start to appear in the
interior portions of the shrub. This results in a healthy plant with strong
stems and greatly decreases the incidence of disease problems.
Shearing is done to provide shape and to keep the shrub looking crisp and
sharp. Assuming that the hedge is at the height your design needs, you
should keep the new growth trimmed back so that it doesn’t look untidy. This
is best done with a hedge clipper. For boxwoods that are still growing into
their final height, you will want to let the new growth remain. Shear
evergreen shrubs such as Boxwood between June 1st and August 15th after new
growth develops and hardens off.