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| Cercis canadensis Redbud |
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Pruning Shrubs
Pruning recommendations for most deciduous shrubs consist of crown thinning, gradual renewal and rejuvenation pruning. In crown thinning, a branch or twig is cut off at its point of origin from either the parent stem or ground level. 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. 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.
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:
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Cercis canadensis
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Redbud
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Chaenomeles japonica
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Japanese quince
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Chionanthus virginicus
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Fringe Tree
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Forsythia spp.
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All forsythia species
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Lonicera spp.
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Honeysuckle
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Rapheolepis indica
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Indian hawthorn
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Rhododendron spp.
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Azaleas and rhododendrons
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Rosa spp.
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Rambling rose species
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Spiraea spp.
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Early white spirea species
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Viburnum spp.
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Viburnum species
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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:
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Abelia X. grandiflora
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Glossy abelia
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Buddleia davidii or B. globose
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Butterfly bush
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Hibiscus syriacus
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Shrub althea
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Hydrangea arborescens
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Hills of Snow
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Hypericum spp.
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St. Johnsworlth
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Lagerstroemia indica
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Crape myrtle
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Rosa spp.
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Bush rose
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Vitex agnus-castus
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Chaste tree
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| Portland, Oregon Rhododendron |
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| Portland, Oregon Hydrangea |
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