Thinning
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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 plants 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
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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. |
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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 seasons 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
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 |
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Some examples of shrubs that bloom on last seasons
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
Pearlbush
Kerria
Honeysuckle
Star magnolia
Mockorange species
Andromeda species
Azaleas
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
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 |
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Some examples of shrubs that bloom on current seasons
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
Symphoricarpos
Tamarix hispida
Tamarix odessana
Vitex agnus-cactus
Glossy abelia
Butterfly bush
Japanese beauty bush
Bluebeard
Summersweet
Shrub althea
Hills of Snow
Peegee Hydrangea
Saint Johnswort
Crape myrtle
Bush rose
Anthony Waterer Spirea
Mikado Spirea
Coralberry
Snowberry
Kashgar
Odessa
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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