Proper Pruning Techniques part 4

Author: Douglas F. Welsh, Extension Horticulturist; Everett Janne, Extension Landscape Horticulturist (retired)

Pruning Shrubs

Deciduous and Flower Shrubs

Pruning recommendations for most deciduous shrubs consist of thinning out, gradual renewal and rejuvenation pruning. In thinning out, a branch or twig is cut off at its point of origin from either the parent stem or ground level (Figure 8). This pruning method results in a more open plant; it does not stimulate excessive new growth, but does allow room for growth of side branches. Considerable growth can be cut off without changing the plant's natural appearance or growth habit . Plants can be maintained at a given height and width for years by thinning out. This method is best done with hand pruning shears, loppers or a saw, but not with hedge shears. Thin out the oldest and tallest stems first.

In gradual renewal pruning, a few of the oldest and tallest branches are removed at or slightly above ground level on an annual basis (Figure 8). Some thinning may be necessary to shorten long branches or maintain a symmetrical shape.

To rejuvenate an old, overgrown shrub, remove one-third of the oldest, tallest branches at or slightly above ground level before new growth starts.

The general pruning procedure shown for crape myrtle (Figure 9) applies to many large shrubs and small tree species. If a shrub is grown for its flowers, time the pruning to minimize disruption of blooming. Spring flowering shrubs bloom on last season's growth and should be pruned soon after they bloom. This allows for vigorous summertime growth and results in plenty of flower buds the following year.

Some examples of shrubs that bloom on last seasons's growth are:

Cercis canadensis Redbud

Chaenomeles japonica Japanese quince

Chionanthus virginicus Fringe Tree

Forsythia spp. All forsythia species

Lonicera spp. Honeysuckle

Rapheolepis indica Indian hawthorn

Rhododendron spp. Azaleas and rhododendrons

Rosa spp. Rambling rose species

Spiraea spp. Early white spirea species

Viburnum spp. Viburnum species

Some shrubs that bloom after June usually do so from buds which are formed on shoots that grow the same spring. These shrubs should be pruned in later winter to promote vigorous shoot growth in spring. Examples of shrubs that bloom on current season's growth include:

Abelia X. grandiflora Glossy abelia

Buddleia davidii or B. globose Butterfly bush

Hibiscus syriacus Shrub althea

Hydrangea arborescens Hills of Snow

Hypericum spp. St. Johnsworlth

Lagerstroemia indica Crape myrtle

Rosa spp. Bush rose

Vitex agnus-castus Chaste tree

(from The Agriculture Program of the Texas A&M University System - Extension Horticulture Information Resource --- used by permission)

Gardening Aids