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Ch. 8, pp. 9 - 11

Deciduous Shrubs
The pruning recommended for most deciduous shrubs consists of thinning out, gradual renewal, and rejuvenation pruning. In thinning out, a branch or twig is cut off either at its point of origin from the parent stem, to a lateral side branch, to be “Y” of a branch junction, or at ground level. Thin out the oldest and tallest stems first, to allow for growth of vigorous side branches. This method of pruning results in a more open plant and does not stimulate excessive new top growth. Considerable growth can be cut out without changing the plant’s natural appearance or habit of growth. Plants can be maintained at a given height and width for years by thinning out. This method of pruning is best done with pruning shears, loppers, or a saw (not hedge shears).
Gradual Renewal
Gradual Renewal
In gradual renewal pruning, a few of the oldest and tallest branches are removed at or slightly above ground level on an annual basis. Some thinning may be necessary to shorten long branches or maintain a symmetrical shape.
To rejuvenate an old, overgrown shrub, 1/3 of the oldest, tallest branches can be removed at or slightly above ground level before new growth starts.
When the shrub to be pruned is grown for its flowers, the pruning must be timed to minimize disruption of the blooming. Spring flowering shrubs bloom on last season’s growth and should be pruned soon after they bloom. This allows for vigorous growth during the summer, to provide flower buds for the following year.
The general pruning procedure, illustrated below for crape-myrtle, applies to many other large shrubs and small trees of similar structure

Proper Method of Pruning Crape-myrtle
Poper Method of Pruning Crape-myrtle
The plant, pictured before pruning, needs to have all weak and dead stems removed.

Same shrub after removal of weak and interfering wood, also base sucker growth

Results of proper pruning - graceful, vigorous growth with distinctive shape
Some examples of shrubs that bloom on last season’s growth:
Cercis chinensis
Chaenomeles japonica
Chionathus virginicus

Deutzia species
Exochorda racemosa
Forsythia species
Derria japonica
Lonicera species
Magnolia stollata
Philadelphus species
Pieris species
Rhododendron species
Rosa species
Spiraea species
Syringa species
Tamarix parviflora
Viburnum species
Weigela florida
Chinese redbud
Japanese quince
Fringe tree
Spring-flowering dertzias
Star magnolia
Mockorange species
Andromeda species
Rambling rose species
Early white spirea species
Lilac species
Small-flowered tamarix
Old-fashioned weigela
Some shrubs that bloom after June usually do so from buds which are formed the same spring. Such shrubs should be pruned in late winter to promote vigorous growth in the spring.
The general pruning procedure, illustrated below for crape-myrtle, applies to many other large shrubs and small trees of similar structure

Improper Method of Pruning Crape-myrtle
Improper Method of Pruning Crape-myrtle
Cutting at the dotted line is the usual course taken by those who prune shrubs

The same plant after bad pruning, as indicated above. The sucker growth remains.

Result: the lovely natural shape of the shrub is lost, and bloom will be sparse
Some examples of shrubs that bloom on current season’s growth:
Abelia x grandiflora
Buddleia davidii, globosa
Callicarpa japonica
Clethra alnifolia
Hibiscus syriacus
Hydrangea arborescens
Hydrangea paniculata

Hypericum species
Lagerstroemia indica
Rosa species
Spirea bumalda
Spiraea japonica
Tamarix hispida
Tamarix odessana
Vitex agnus-cactus

Glossy abelia
Butterfly bush
Japanese beauty bush
Shrub althea
Hills of Snow
Peegee Hydrangea
Saint Johnswort
Crape myrtle
Bush rose
Anthony Waterer Spirea
Mikado Spirea
Chaste tree
Evergreen Shrubs
For most evergreen shrubs, thinning is the most desirable procedure. Some evergreens can be sheared when a stiff, formal appearance is desired; however, they will still need to be thinned occasionally. Both evergreen and deciduous shrubs grown for foliage should be pruned in late winter before new growth starts. Minor corrective pruning can be done at any time.

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