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Pruningshrubs Part 1

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Pruningshrubs Part 1

  1. 1. Pruning Ornamental Shrubs and Vines By Neil Bell Community Horticulturist Marion and Polk Counties
  2. 2. Contents:What is pruning? Why prune?Timing of pruning Frequency of pruningPruning principles Pruning referencesSpecific pruning techniques: Shrubs Conifers Vines
  3. 3. What is Pruning? The selective removal of specific parts of the plant to benefit the whole plantPruning is NOT: a way to compensate for inappropriate plant placement!
  4. 4. Plant placement Consider the mature size of plants and available space before you plant!
  5. 5. Why Prune? Remove dead, diseased or broken parts Prune out winter injury
  6. 6.  sucker removal
  7. 7. Enhance a characteristic-coppicing From the French “to cut” used to enhance leaf, stem effect Shrub dogwood
  8. 8. Coppicing to enhance leaf size…Cotinus coggygria (smokebush)
  9. 9. Develop unusual forms espalier, bonsai topiary
  10. 10. Train a young plantRosa mulliganii (Before) Later…
  11. 11. Stimulate new wood  thinning  rejuvenation
  12. 12. Size Control short term only!
  13. 13. Why Prune at all?Pruning is a stress on plants March June
  14. 14. Plant will grow unassisted to natural form is that really desirable? Holodiscus discolor (Oceanspray)
  15. 15. Timing of PruningDepends on: 1. Flowering habitBlossoms on old wood Blossoms on new wood Viburnum plicatum Phygelius
  16. 16. 2. Objectives  remove dead wood anytime 3. Rate of healing  quickest response is just prior to beginning of new growth
  17. 17. 4. Risk of suckers  greatest in e. spring  less problem in summer  Malus, Syringa 5. Risk of winter injury  Rosa, Hebe, Salvia etc.
  18. 18. Frequency of Pruning1. Prune only as needed  know what you want to achieve 2. Age of plant  Young plants
  19. 19. 3. Type of plant  clipped hedges4. Need for size control  maybe not practical!
  20. 20. Most importantly: know what the pruning will do!
  21. 21. Know the plant and keep a good reference around…  don‟t obsess about “rules”  observe growth/flowering  observe the response
  22. 22. Principles of PruningGrowth of woody plantsDirecting growthPrincipal pruning cutsAdaptations to damage and disease
  23. 23. Growth habit of woody Plants 2010 Lilac: Syringa vulgaris Spring 2011 20092008  Largest buds at branch tips2007  Not all buds develop  twig diameter increases with age 2006
  24. 24. color change in woodRibes sanguineum
  25. 25. Parts of a branch Terminal Bud (auxin) Axillary Bud Node Flower Bud Latent Bud
  26. 26. Directing growth:Cutting above a bud 450 angle Too angular Too low Too high Good! Alternate-budded plants Opposite
  27. 27. Response to pruningremoval of materialcauses growth elsewhereremoving terminal budallows lateral developmenttopmost remaining budgrows most strongly alternate opposite
  28. 28. Another way to force branching…
  29. 29. Cutting back branches Cut back always to a part that will continue to grow At least ½ the size of the part being removed
  30. 30. Positioning shears and making a cut  avoid leaving stubs  use the correct size tool
  31. 31. Pruning cuts
  32. 32. Thinningremoval of entire stem or section of stemopens up the plant to admit lightreduces overall height and promotes regrowth
  33. 33. Heading (selective) Cutting back to a bud or shoot Promotes branching, will “fill in” the plant
  34. 34. ShearingNon-selective heading: dense growth at branch tipsUnnatural form, appropriate for formal hedges
  35. 35. Pinching Specializedtechnique for succulent tissues Thinning Promotes branching Heading Pinching
  36. 36. Renovation Cutting all canes back to near base to renew all growth Very harsh technique: not appropriate for all plants!
  37. 37. February, 2009 April, 2009
  38. 38. January, 2010
  39. 39. Adaptations to damage and disease Plants have no “wound healing” process: healing in a sense of replacing or repairing injured tissues. Plants seal off damaged tissue rather than heal it.
  40. 40. CODIT Compartmentalization Of Decay In Trees Plants are highly ordered, compartmented Instead of healing, plants compartmentalize injured and infected tissues.
  41. 41.  callus tissue is produced on the wound margin
  42. 42. Wound paints and dressings evidence for use is inconclusive no given treatment fulfills all requirements 1. Prevent decay 2. Speed wound closure 3. Inhibit insect or diseases
  43. 43. Pruning ShrubsWhen and how to prune a shrub depends on…1. Flowering habit 2. Growth habit Calycanthus x raulstonii Salix caprea var. pendula
  44. 44. Determining time to prune flowering shrubs The “flowering habit”1. Blooms on “old” wood: after flowering2. Blooms on “new” wood: early spring The issue is: When does the shrub form the flower buds?
  45. 45. Distinguishing between “old” and “new” wood Spring blooming shrubs develop buds in fall  Tend to bloom early in season Summer/fall blooming shrubs form buds as they grow  Tend to bloom later in season Chaenomeles-spring bloom Spiraea x bumalda -summer bloom
  46. 46. Length of bloom periodSpring bloomers: 2 weeks? Summer bloomers: often more than a month Rhododendron Fuchsia magellanica
  47. 47. Flower type: terminal or axillaryCrabapple (Malus)-winter Hydrangea paniculata-winter
  48. 48. “New” wood versus “old” wood Terminal flowers: Current season wood i.e. Buddleja (July-September) Lateral flowers: One year-old wood i.e Chaenomeles (February-May)
  49. 49. Distinguishing between“New” wood and “old” wood  Flowering time: spring or summer  Length of flowering period  Axillary or terminal flowers Some shrubs cause confusion! (i.e Hydrangea macrophylla)
  50. 50. Genera with species that flower on both new and old wood New: Repeat bloomers Rosa Old: Once-blooming, species New: H. paniculata, H. arborescensHydrangea Old: H. macrophylla New: S. japonica, S. „Bumalda‟ Spiraea Old:S. x vanhouttei, S. „Arguta‟
  51. 51. How to prune: depends on growth habit Cane growers: Permanent f‟mwork: i.e. Forsythia i.e. Rhododendronusually deciduous Subshrub: EG or deciduous i.e Perovskia EG or deciduous
  52. 52. Cane growers are easy to identifyHydrangea macrophylla Philadelphus
  53. 53. “Cane” growersDeutziaForsythiaHydrangea (lacecap/mophead)Kolkwitzia (Beautybush)Philadelphus (Mock orange)Physocarpus (Ninebark)Sambucus (Elderberry)Spiraea (Bridal Wreath)Rosa (Rose)Viburnum
  54. 54. Permanent framework Have a “tree-like” structure Do not renew themselves from the base Often are evergreen shrubs Pieris japonica Rosmarinus officinalis „Arp‟
  55. 55. Permanent Framework Ceanothus (Wild lilac)) Cistus (Rockrose) Daphne Hamamelis (Witchhazel) Hebe Hibiscus (Rose of Sharon) Ilex (Holly) Lavandula (Lavender) Pieris (Andromeda) Rhododendron (and azalea) Rosmarinus (Rosemary)
  56. 56. Some are deciduous… Hibiscus syriacus (Rose of Sharon)Hamamelis (witchhazel)
  57. 57. Subshrubs Have a woody framework Produce flowers on new growth Salvia microphylla Phygelius „Sensation‟
  58. 58. Some examples of subshrubs Artemisia (Wormwood) Caryopteris (Bluebeard) Ceratostigma (Plumbago) Fuchsia magellanica (etc) Gaura lindheimeri Heptacodium (7 Sons Plant) Hydrangea paniculata Lavatera (Tree mallow) Salvia (Sage) Perovskia (Russian sage) Penstemon Phygelius (Cape Fuchsia) Vitex (Chaste tree) Penstemon spp. Zaushneria (California Fuchsia)
  59. 59. Pruning Cane growers  Remove: • dead • damaged • crossing • twiggy growth  Thin oldest canes • 1-2 per yearDeutzia „Pride of Rochester‟
  60. 60. Philadelphus lewisii
  61. 61. Good growth, but dense at base Remove basal canesSambucus nigra „Madonna‟
  62. 62. Crowded at base
  63. 63. Another example…  Basal growth removed  Weak canes removed Deutzia „Pride of Rochester‟
  64. 64. Too dense thin canes Too much thinning  avoid topping canes!
  65. 65. Shearing cane growers
  66. 66. Effects of topping canes (i.e. heading) Viburnum opulus Few flowers!
  67. 67. February April

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