When to Trim Shrubs

Maintaining Overall Shape

• Prune to maintain overall shape of shrubs at any time of the year. This includes removing any dead or diseased branches or removing branches that extend beyond the desired shape of the plant. Keep in mind that not all shrubs have the same shape, and you should work to maintain the natural shape of the shrub. Shrubs like forsythia have a natural arch to branches and should not be trimmed to form a ball or rounded canopy.

Spring-Blooming Shrubs

• Trim shrubs like forsythia, lilac and mock orange that bloom in spring or early summer directly after blooming. Spring-blooming shrubs set buds in mid- to late summer for the next year's blooms. Any pruning or trimming done after the first week of July may remove young buds and diminish blooms for the next season.

Summer- or Fall-Blooming Shrubs

• Prune summer- or fall-blooming shrubs like butterfly bush, Rose of Sharon and summersweet in early spring before new growth occurs. Summer-blooming shrubs bloom on new growth. Pruning in early spring promotes new growth and vigorous blooms.

Procedure

• Use clean, sterile clippers when pruning or trimming shrubs. Dip clippers in a solution of one part household bleach to seven parts of water between cuts. Making a clean cut with sterile clippers reduces the risk of introducing disease in open cuts.

  Trim terminal shoots on a 45-degree angle about 1/4 inch above a bud. Sharp angles take longer to heal and increase the risk of exposure to disease. A 45-degree angle allows water to run off the cut, and encourages new growth to form from lateral buds 6 to 8 inches below the cut.

  Control the direction of new growth by selecting a lateral bud facing the direction in which you wish new growth to appear, and cut 1/4 inch above the bud. If two buds are present facing opposite directions, remove the bud that you do not want to grow.

Severe Pruning

• Severely prune overgrown shrubs to rejuvenate and encourage lush new growth. Shear to the ground in early spring, if necessary. Yellow and red twig dogwood benefit from shearing nearly to the ground each year. This encourages new woody growth and creates a compact plant with showy wood.