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.
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 holiday decorations!
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 branches.
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.
See our tips for Pruning
Our Favorite Varieties:
Common Problems of Boxwood
Insects called psyllids will cause cupping of the new growth and can be controlled by spraying with a Bonide Systemic Insect Control spray in mid-May and repeating in 10 days.