Part I - Oregon State University Extension Service

Pruning permanent framework
Many of these plants form a dome-shaped canopy
Generally assume regular shape
Ceanothus „Julia Phelps‟
Pieris „White Cascade‟

Remove:
• dead
• damaged
Lavender
Lavandula spp.
Cistus „Silver Pink‟
Removal of errant shoots help shape
1
“Cubist” pruning is common…
Or, the meatball variation…
Think about flowering time before pruning!
2
Shearing removes form, but hopefully not flowers…
Pittosporum tenuifolium
Arbutus unedo (Strawberry tree)
„Silver Sheen‟
Pruning subshrubs
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Small subshrubs which may be sheared:
have woody base, but bloom
on current season‟s shoots
some become larger and more
woody in mild climates
avoid pruning until after
risk of severe freeze
Epilobium canum
Buddleia nivea
Penstemon pinifolius
Remove most shoot growth to base
Before…
August 2010
January 2011
After…
3
Larger subshrubs…
Caryopteris x clandonensis
Spiraea
Perovskia atriplicifolia
Large subshrubs
Buddleia „Pink Delight‟

Heptacodium miconioides
Remove dead stems, prune hard in spring
Lavatera: early spring
10 minutes work!
Note where cuts made…
Later…
Look how much growth is removed!
4
Suckering shrubs
Naturally thicket-forming plants

Includes:
• Aralia spp.
Clerodendrum spp.
Kerria japonica
• Rhus spp.
• Rubus spp.
• Symphoricarpos spp.
• Syringa vulgaris
• Zenobia pulverulenta
•
•
Heptacodium miconioides
Rhus typhina „Laciniata‟
Pruning Conifers
For pruning purposes, there are two types:


Dig suckers
Use barriers
Needle-foliage Conifers: Pine Family
Abies: The Firs
Cedrus: True Cedars
Picea: The Spruces
Pinus: The Pines
Pseudotsuga: Douglasfir
Tsuga: The Hemlocks
Needle-like leaves
Whorled branches
Scale-like foliage
Random branches
When sited correctly, rarely need pruning
Abies pinsapo „Glauca‟
The biggest mistake: pruning into un-needled growth
Pinus thunbergii „Thunderhead‟
5
Pine Family
To dwarf plant and fill in
canopy, pinch back new
growth at “candle” stage
Do not cut into old, un-needled parts of stem!
Candle pruning makes a conifer…

dwarfer

bushier
Candles on pines are easily broken at this stage
Some conifers revert as well…
Scale-foliage Conifers: Cypress Family
Calocedrus

Incense Cedar

Hinoki Cypress

Leyland Cypress

many, many species/forms

Arborvitae, Western Redcedar
Chamecyparis
Cupressus
 Monterey, Italian Cypress
X Cupressocyparis leylandii
Juniperus
Alberta spruce
Thuja
6
Cypress family plants respond well to
light trimming and make good hedges
Effects of hard pruning:
Don‟t
prune into
older un-needled
parts of plant!
Cutting back hedge
Limbing up too-big shrub
Conifers that respond to cutting to older wood:
Pruning Vines
Taxus: Yews
Sequoia: Redwood
Cryptomeria:
Japanese cedar
7
Pruning need depends on vigor, climbing habit…
Consider the climbing habit of the plant:
Non-clinging plants: Roses
Wisteria
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
rampant growing
permanent framework
Jasminum x stephanense
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
many thin canes
cane-grower
Twining growth habit:
Clinging vines
Clematis Jasminum
Humulus Trachelospermum
Lonicera Wisteria
Campsis (aerial rootlets)
 (will also sucker)
Hydrangea anomala (aerial rootlets)
Hedera (aerial rootlets)
Parthenocissus (tendrils)
Schizophragma (aerial rootlets)
Tendrils:
Ampelopsis
Passiflora
Vitis
The support structure and vine must match!
Little or no pruning required
Climbing roses
8
A trellis can be very simple…
Old trees make a good
makeshift trellis, too
Climbers-modern:
Climbing roses
very tall bush roses, repeat
 renew framework regularly

Rambling Roses
annual cane production
train stems flat
 remove flowered stems
 thin/shorten excess canes
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Spreading out stems horizontally encourages branching
Climbing Rose:
„Westerland‟
Modern Climber
i.e. blooms on new wood
Early spring…
9
Rambling Rose
„Dorothy Perkins‟
Later…
Once-blooming
June 2004
Sept. 2004
July 2005
July 2006
For a full arbor you
will need to plant on
both sides
10
Twining vines
Clematis armandii
Over time, many twining climbers form a “mushroom”
As with other vines,
match the vine with
available space
Jasminum x stephanense
Or, the shape of a TV antenna…
Young vines: shoot placement
11
Lonicera japonica
Pruning vining Clematis
In bloom, June
For pruning purposes, 3 “groups”
based on flowering time:
Spring: (Group 1)
C. armandii, C. montana
Repeat bloom: (Group 2)
Large-flowered hybrids
C. „Nelly Moser‟
Summer-Fall: (Group 3)
C. x jackmanii, C. texensis
C. paniculata, C. viticella
After pruning
A simple trellis…
Pruning vines: Clematis Group 2 (and 1)
Pruning Clematis-Group 1 and 2

Remove weak growths
stems to well—spaced framework
Thin
12
Pruning Clematis Group 3
Prune low to a pair of
strong buds early spring


Remove dead stems
Pruning Clematis-Group 3
Training Wisteria
Trees make handy trellises…
Brickell and Joyce
DK Publishing, 1996
ISBN 1-56458-331-7
13
Brown and Kirkham
Timber Press, 2004
ISBN 0-88192-613-2
Cass Turnbull
Sasquatch Books
ISBN 1570613168
Other references:
PlantAmnesty
http://www.plantamnesty.org/

Pruning tips
PNW-International Society of Arboriculture
http://www.pnwisa.org/


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Pruning information
Publications
Lists of Consulting Arborists
The End!
Pruning Rhododendrons
and Azaleas
Ceanothus griseus „Kurt Zadnik‟
14
Rhododendron stem and bud structure
Pruning Rhododendrons and Azaleas

Removal of spent flowers
promotes branching
Prune after flowering-remove
leading branches at a whorl

Pruning should be done
over a 2-3 year period

Prune
above a whorl of
leaves to avoid leaving a stub
The too-big Rhododendron
correct
incorrect
Be careful about shearing…
1. Make it a focal point!
2. Too big or too dense?
 remove dead wood,
thin branches
15
3. Shorten tallest branches
 cut to lower laterals
5. Turn it into a small tree
 on old, large specimens, remove lower limbs,
dead wood, thin canopy
4. Remove all new growth
 time consuming!
6. Renovation
 cut plant to ground
 poorly pruned shrubs
Some years later…
H. macrophylla:
Pruning Hydrangea
Recall that pruning time will vary with the species!


Remove spent flowers
Thin 1-2 canes
H. paniculata
H. macrophylla
=previous season
H. paniculata
=current season


treat like subshrub
Cut canes to 2 buds
16
Remove flower heads
Remove oldest cane(s)
“Hard” pruning of
H. macrophylla
in spring…
Pruning Roses

hybrid tea
=Reduced flower number
17
“Once” versus “repeat” flowering
Refers to whether a rose bears flowers on
•
•
one-year-old wood (once-blooming)
current season wood (repeat blossoming)
Hybrid Tea, Grandiflora, Floribunda Roses

like all other roses, these are cane growers
remove dead canes
oldest canes may
be cut out
 leave 3-4 canes
 space around plant
 cut back to 18”-2‟


Once blooming: June
Repeat bloom-all summer
Sucker removal
1. Late summer
3. mid-February
2. Fall
4. mid-February
The final product
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