How (Not) To Prune Your Trees and Shrubs

Transcription

1 Slide 1 How (Not) To Prune Your Trees and Shrubs (Part 1) Master Gardener Training 1 How Not to Prune Your Shrubs

2 Slide 2 Right way and wrong way to prune 2 Right way to prune, and a wrong way to prune!

3 Slide 3 Why prune? 3 Before starting any pruning job, ask yourself: Why prune? Plants don t need to be pruned humans prune because we have artificial goals.

4 Slide 4 Reasons for Pruning Removal of dead, diseased, or broken branches Removal of dead, diseased, or broken branches. Prevention of damage to life and property.

5 Slide 5 Reasons for Pruning Plant Health Plant health: Removal of diseased plant parts Avoiding limb-limb abrasion by eliminating crossing branches Reducing leaf/branch density for air circulation Reducing leaf/branch density for light penetration

6 Slide 6 Reasons for Pruning Size Control Size and plant form control Match size with landscape function Aesthetics of scale, form, etc. Space available is limited Visibility

7 Slide 7 Reasons for Pruning Remove undesirable growth 7 Undesirable branches prevent maintenance, injure pedestrians.

8 Slide 8 Reasons for Pruning: Rejuvenation 8 Vegetative rejuvenation - re-invigoration. Thin out overgrowth.

9 Slide 9 Reasons for Pruning Stimulate Flowering 9 Stimulate flowering. Promote younger, more productive growth. Removal of developing fruits promotes flower buds.

10 Slide 10 Reasons for Pruning Training for future growth 10 Newly-planted trees are trained to produce optimum future growth.

11 Slide 11 Reasons for Pruning Protecting utilities 11 Prevent obstruction of power lines

12 Slide 12 Reasons for Pruning? 12 All trees and shrubs have natural shape. Proper pruning should take this into account, so that the pruner works WITH the natural shape, and not AGAINST it.

13 Slide 13 Topiary 13 That being said Topiary: the art of training and clipping trees and shrubs into various geometric or free-form shapes.

14 Slide 14 Topiary 14 Topiary in use during Pan Am Games in Columbus, OH in Represents a painting by Seurat.

15 Slide 15 Topiary? Not! 15 Another type of shaping is Green Meatball pruning. Not very attractive.

16 Slide 16 Green Meatballs 16 Many reasons green meatball pruning is done. Relieves stress.

17 Slide 17 I have no words for this Green saucer pruning very stressed person lives here!

18 Slide 18 Visibility 18 Office of Homeland Security recommends pervert pruning, so you can see if perverts are hiding behind shrubs.

19 Slide 19 Basic Concepts: Apical Dominance Growth at the shoot tip dominates and suppresses growth of lateral shoots. Referred to as apical dominance Suppressed axillary buds Active apical bud Apical dominance: Inhibition of growth of lateral buds (shoots) by terminal bud (shoot)

20 Slide 20 Basic Concepts: Lack of apical dominance Pruning removes the apical meristem, the source of plant hormone. With no hormone coming from the apex, axillary buds develop, giving rise to a bushier plant Apical bud is removed by pruning Axillary buds develop Pruning removes the apical meristem, the source of plant hormone. With no hormone coming from the apex, axillary buds develop, giving rise to a bushier plant

21 Slide 21 Basic Concepts: Protect Collar Make cut close to, but not invading the ridge of tissue called the collar Where branch comes from trunk is area called branch collar. When pruning, this area must be protected. Branch collar is a zone where lots of cell division can occur, prevent decay from spreading.

22 Slide 22 Basic Concepts: Callus Development Collar will be the source of callus tissue Callus is like a permanent bandage Collar will be the source of callus tissue. Callus is like a permanent bandage.

23 Slide 23 Basic Concepts Compartmentalization Wood structure walls off wounds to reduce incursion of decay microorganisms into heartwood Collar needs to remain intact to allow compartmentalization CODIT : Compartmentalization of Decay in Trees Compartmentalization of Decay in Trees: CODIT

24 Slide 24 Compartmentalized Not Compartmentalized Proper cuts allow tree to seal off wound quickly, so decay is compartmentalized into one small area. Improper cuts delay closing of wound, which allows decay to spread throughout the trunk.

25 Slide 25 Pruning timing 25 When to prune? When the saw is sharp! Prune to maximize flower display. Prune during dormant season so can see branch structure.

26 Slide 26 Pruning timing: spring bloomers 26 Spring flowering plants (magnolia, dogwood, lilac, rhododendron/azalea) prune after flowering.

27 Slide 27 Pruning timing: summer bloomers 27 Summer flowering plants (golden raintree, Franklinia, rose, hydrangea) prune in early spring before flowering.

28 Slide 28 Pruning timing: pinching evergreens 28 Pinch new shoots/candles of conifers in early May. Otherwise, prune evergreens when wood is not frozen.

29 Slide 29 Pruning timing: bleeders 29 Bleeders (maple, birch, dogwood, elm, walnut) prune in mid-summer, late fall.

30 Slide 30 Special Plants 30 Hydrangeas: different types need to be pruned at different times. Hydrangea types include mop heads, vines, P.G.s, and oakleaf.

31 Slide 31 Pruning timing: avoid late summer 31 Avoid late summer pruning (forces new growth, which may receive winter injury)

32 Slide 32 How to prune...the right tools 32 How? Right way and wrong way. Use the right tools.

33 Slide 33 Hand shears 33 Hand shear pencil thick Right = hook and blade, scissor action, cuts clean Left = anvil, crushes wood, doesn t make close cuts

34 Slide 34 Loppers 34 Loppers = for leverage. For wood up to 1 to 1.5 inch.

35 Slide 35 Hedge shears 35 Hedge shears = for formal hedges only.

36 Slide 36 When to use hedge shears Hedge shears for formal hedges only

37 Slide 37 When NOT to use hedge shears 37 Trees and shrubs that have been sheared.

38 Slide 38 Pruning saws 38 Pruning saw: cuts wood > 1 inch diam. Isn t a carpenter s saw.

39 Slide 39 Pole pruners/saws 39 Pole pruner, pole saw. Used for reaching high branches without leaving the ground.

40 Slide 40 Chainsaws 40 Chain saw large jobs. Dangerous! Homeowners don t have training to handle chainsaw up in tree, and shouldn t do it. Make sure chainsaw has all safeties engaged.

41 Slide 41 Pruning shrubs 41 Pruning shrubs: secret is to retain natural shape.

42 Slide Shearing causes thick tangle at top (buds stimulated to grow). Shades lower part; gives weak, leggy growth.

43 Slide 43 Pruning cuts Heading Back Thinning General types of pruning cuts: Heading back to above a promising bud or side branch. Thinning to a main branch or the ground. Remove the entire branch at its point of origin.

44 Slide 44 Pruning cuts Heading back A pruning cut made between the shoot tip and the point of origin of that shoot Should be made just above a lateral branch or bud Bud direction aims shoot growth Generally remove up to 1/3 of the height Heading back: a pruning cut made between shoot tip and point of origin of that shoot.

45 Slide 45 Heading back to a lateral branch or bud Heading back to a lateral branch or bud. Reduces overall size of the plant. Do not amputate make cuts back to a worthy side branch.

46 Slide 46 Thinning out Thin out weak, diseased, and damaged branches at ground level. 46 Thin out weak, diseased, damaged branches of multi-stemmed shrubs at ground level.

47 Slide 47 Pruning cuts: technique YES NO NO NO Heading back cuts: correct and incorrect Left side: Head back to a bud growing outwards. Make cut ¼ inch above bud, slightly slanted toward bud. Do not cut too close to bud (bud may dry out and die). Don t leave too much stub (may sucker, or may dry out and begin to decay). Right side: With bypass pruner, put blade part nearest trunk, to make good, clean cut. Do not make a flush cut; cut outside of branch collar.

48 Slide 48 Don t leave a stub 48 Don t leave a stub. This branch was undesirable because of direction it was growing in. It should have been removed completely at point of origin (thinning cut). Note swollen branch collar at base of side branch.

49 Slide 49 Hedge shearing 49 Creating a hedge. Cut top of hedge at pre-determined height. Use string that s been straightened to plumb with level to keep a straight edge. Tilt shears at very slight angle and go across top. Follow up with shearing both sides, running hedger up and down as move forward. Again, using strings or stakes to keep sides straight.

50 Slide 50 Hedge shearing 50 Proper hedge should be wider at base. If top is wider, base is shaded out, and it will lose leaves/lives shoots.

51 Slide 51 Hedge maintenance 51 Hedge maintenance: trim succulent new shoots 2 or 3 times per summer. Use guides to keep edge straight. Do not use hedge shears to cut woody stems. Informal hedges (not sharp, straight lines) can be sheared once per year, in winter.

52 Slide 52 Thinning cuts Thinning: Complete removal of a shoot at its point of origin (the base of the shoot)

53 Slide 53 Renewal Pruning 53 Renewal pruning of overgrown shrub = 3-year-process.

54 Slide 54 Renewal Pruning: Year 1 54 Year 1: remove all dead, diseased wood. Remove 1/3 of oldest mature branches at ground level.

55 Slide 55 Remove canes at ground level 55 Close-up of older branches being removed.

56 Slide 56 Renewal Pruning: Year 2 56 Renewal pruning, year 2. Thin out 1/3 canes at ground level. Head back new growth from last year to keep shrub from over-growing.

57 Slide 57 Renewal Pruning: Year 3 57 Remove final 1/3 of stems in 3 rd year, end up with completely renewed shrub. Head back whole shrub to maintain size.

58 Slide 58 Rejuvenation pruning 58 Rejuvenation consists of cutting back whole shrub to ground. Immediately reduces size. Will also invigorate shrub.

59 Slide 59 Rejuvenation Pruning 59 That spring, multiple shoots will start growing. Thin out 2/3 of them, keep strongest, most widely spaced 1/3.

60 Slide Only certain shrubs can be rejuvenated: privet, lilac, spirea, forsythia, honeysuckle. These are all the multi-stem shrubs that are so vigorous, they are nearly impossible to kill. You d spend all winter trying to remove only 1/3 of the shoots on this shrub.

61 Slide 61 Take a break Stop here, take a break.

62 Slide 62 Pruning rhododendrons 62 Rhododendrons don t like a lot of pruning. We do a modified type of heading back only when needed. Dead-head spent blossoms as soon as they fade; head back in spring only 1 or 2 nodes down. Never cut into areas of bare stems or sparse foliage. These shrubs will sprout poorly or not at all.

63 Slide 63 Pruning rhododendrons 63 Never cut into areas of bare stems or sparse foliage. These shrubs will sprout poorly or not at all.

64 Slide 64 Evergreens 64 Most evergreen shrubs are unusually shaped. Lots of branches and twigs going in all directions. Do not shear!

65 Slide 65 Prune back to major branch 65 Prune back to major twig/branch. Remove oversized, rubbing branches. Do each branch individually.

66 Slide 66 Beware of dead zone 66 Beware of dead zone! Shaded areas do not regrow.

67 Slide 67 Pines: increasing density 67 Thin, sparse pines occur when put on too much growth in early years. Can NOT prune back, it will not bud out. To thicken sparse conifers...

68 Slide pinch back ½ of candle when shoot is 4-6 inches long (mid to late April in Southern Indiana)

69 Slide 69 Pine pinching 69 Eventually thickens out.