When to Prune Your Woody Shrubs

With the approach of spring, gardeners are eager to head outside to get a head start on the multitude of spring chores awaiting them. One of those may include pruning your woody shrubs.

Although pruning is not necessary every spring, it's the time of year when bare limbs allow you to see the shape of the plant so that you can determine if winter cold, insects, or disease have caused damage, or the natural growth of the plant needs to be managed, or the ornamental appeal of the shrub could be enhanced. If any of these are true, then it is time to prune.

But a word of caution: be careful to prune at the right time. Otherwise, you will lose or reduce that year's blossoms.

Shrubs flowering before May should be pruned as soon as possible after blooming. Pruning in late summer, fall, winter, or early spring removes the flower buds formed last summer. These shrubs include forsythia (Forsythia spp.), hydrangea (Hydrangea arborescens, Hydrangea paniculata), mock orange (Pittosporum tobira), flowering quince (Chaenomeles spp.), spirea (Spiraea spp.), and viburnum (Viburnum spp.).

Summer- and fall-flowering shrubs should be pruned before new growth begins in the spring as the buds form on that new wood. These include abelia (Abelia spp.), beautyberry (Callicarpa americana), butterfly bush (Buddleia davidii), crape myrtle (Lagerstroemia indica), gardenia (Gardenia jasminoides), bigleaf hydrangea (Hydrangea macropylla), nandina (Nandina domestica), and Rose of Sharon (Hibiscus syriacus). All of these bloom on new growth in the current season.

Evergreen shrubs usually only need minimal pruning in early spring. These include boxwood (Buxus simpervirens), Japanese aucuba (Aucuba japonica), camellia (Camellia spp.), Japanese hollies (Ilex crenata cultivars), and azaleas (Rhododendron spp.).

Sometimes, overgrown shrubs need more than a few selected cuts. In this case, renewal pruning, which removes the oldest branches of a shrub by cutting them to the ground leaving younger branches, is required. Although this reduces flowering in the next season, the plant will be healthier in the long run. Shrubs responding well to such pruning include azaleas (Rhododendron spp.), Butterfly bush (Buddleia davidii), forsythia (Forsythia spp.), hollies (Ilex spp.), mock orange (Pittosporum tobira), spirea (Spirea spp.), and weigela (Weigela florida).

There is no need to treat pruning cuts with sealers as they may slow healing. Avoid pruning after July 4 as the new growth may not mature before cold weather sets in and the plant could be damaged. The exception is dead, diseased, damaged, or crossing limbs, which can be removed at any time.

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Written by: Joanne Kollar, Extension Master Gardener volunteer