How to Prune a Boxwood Topiary

Boxwood is an ideal evergreen for sheared topiary use due to the small leaf size. This allows the plant to be sheared lightly and repeatedly while still presenting a dense green surface. Boxwood is a genus of shrubs known botanically as Buxus, and there are more than 30 known species. According to Cornell University, boxwood is slow-growing, so any pruning should always be done with a minimalist approach and long-term consequences in mind. Like all evergreens, when large amounts of boxwood foliage needs to be removed to alter or restore an overgrown topiary form, this must always be done gradually, over several years time.

• 1

  Prune your topiary boxwood in the spring after the last hard frost and into, but not too far past, the early summer. Late summer and fall pruning can spur tender new growth that may not have time to harden off before winter. This makes the new growth susceptible to being killed off, creating unsightly discolorations and holes in your topiary.

• 2

  Use the appropriate pruning tool for the size and intricacy of your boxwood topiary. Small and highly detailed topiary will require the use of small pruning shears to allow access into tight spaces and easy visibility as you work. Long-blade scissor shears are more useful on mid-size to large topiary forms, while electric wand-style shears make quick work when pruning large-scale topiary forms and hedging. Use secateurs or loppers to sever branches up to 3/4 inch in diameter, and a fine-toothed pruning saw for wood that is any larger, to prevent tearing of the cambium.

• 3

  Prune back or remove boxwood branches only when they are inconsistent with the structure of your topiary design or if they are obviously dead, diseased or old and completely defoliated. Sever the unwanted branches down to 1/4 inch above a leaf nod, or all the way down to the joint with the parent branch. Once you cut into wood barren of leaves there is a very high probability that the boxwood will not be able to generate new growth at that point. Carefully consider this before making what may be a permanent structural cut to the plant.

• 4

  Control the perimeter shape and surface texture of your topiary by shearing the terminal tips of the branches where new growth appears. This has the effect of creating branching and new leaves, creating a denser green surface. Do not shear your topiary more frequently than once a year as the more you shear, the denser the outer foliage becomes and the interior foliage will die back for lack of sunlight and air flow. Hold the cutting blade parallel with the boxwood surface to create flat plane cuts, and hold it at varying angles for curvilinear shapes.