1. Janet B. Carson Extension Horticulture Specialist
The ABCs of Pruning
Janet B. Carson
Extension Horticulture Specialist 1

2. ABCs A: - Know WHY you are pruning! B: - Know WHEN you should prune!
C: - Know HOW to prune each plant!

3. WHY: (e.g. crossing branches) 1. Remove dead or diseased wood
2. Eliminate structural problems
(e.g. crossing branches)
3. Eliminate hazards (e.g. pedestrian conflicts)
4. Improve flower display
5. Increase light levels in interior
6. Reduce plant size
7. Aesthetics (shaping)

4. WHY?

5. Fit the tool to the job

6. When to prune flowering shrubs:
Spring bloomers set flowers on older wood
*Normally set flower buds in late summer or early fall.
Summer bloomers usually bloom on the current seasons growth.

7. Plants that flower on ‘old’ wood
(flower buds are formed in the late summer/fall, carried through the winter, and then flower in spring)
Spring spiraea
forsythia
Flowering quince
Big leaf hydrangea
Oakleaf hydrangea
azalea

8. Plants that flower on ‘old’ wood
Azalea
Forsythia
Redbud
Flowering quince
Honeysuckle, winter
Magnolia
Mock orange
Fringetree
Spiraea (Bridalwreath & Vanhoutte)
Lilac
Hydrangea (Big leaf & Oakleaf)
Rhododendron
Viburnum
Weigela
Prune AFTER flowering !

9. Plants that flower on ‘new’ wood
(flower buds are formed on current season growth)
Summer spiraea
Buddleia
Crape myrtle

10. Prune BEFORE new growth begins ! (usually done in late February)
Plants that flower on ‘new’ wood
Abelia
Rose-of-Sharon
Butterfly bush
Clethra
Sumac
Crape myrtle
Roses
Spiraea (summer flowering types)
Vitex
Hydrangea (Panicle or Smooth)
Prune BEFORE new growth begins !
(usually done in late February)

11. Pruning non-flowering evergreens
Light shaping or shearing—anytime
Severe pruning (more than 1/3) should be done late winter-early spring for quick recovery

12. Needles versus broadleaf plants

13. Needle type evergreens
Only have buds on green growth
Limited in how severe you can prune

15. Broadleaf plants have replacement buds

17. Prune at the branch collar

18. No pruning paint needed! Make nice clean cuts.

19. Major considerations:
HOW does the shrub grow? (does it have a main trunk or is it a cane producing plant with multiple trunks)
2. WHEN does the shrub flower? (does it bloom in the spring, summer or fall)

20. Prune based on shrub habit. How does the plant grow?
Foster Holly
corylopsis

21. Cane producing shrubs benefit from rejuvenation pruning

22. Cane Producing Shrubs (plant rejuvenates readily from the ground)
Mock orange
Forsythia
Redtwig dogwood
Big leaf hydrangea
Japanese Kerria
Spiraea
Deutzia
Flowering quince
Nandina
Itea
Abelia
Butterfly bush

23. Cane producing shrubs respond well to renewal pruning
Cane producing shrubs respond well to renewal pruning. Renewal pruning rejuvenates the plant and typically results in better flowering and fruiting.

24. Renewal pruning involves removing the largest branches or canes at the ground line.

26. Do not leaves stubs, and, generally don’t remove more than 1/3 of ‘canes’ at any one time.

27. Renewal pruning
Before
After

29. Proper pruning gives more blooms.

30. Shrubs that lend themselves to selective thinning.
Viburnums
Cleyera
Rose-of-Sharon/Althea
Ligustrum
Azalea
Rhododendron
Hollies
Japanese Maples

31. Selective thinning involves cutting back to a lateral branch or to the bud. Selective thinning can reduce the plant size while maintaining a natural habit.

33. More formal, and, once you start, difficult to break-out of habit.
Shearing
More formal, and, once you start, difficult to break-out of habit.

34. Shearing typically requires different tools.

35. Formal Pruning

37. Crape-murder

38. For Crape myrtles:
Choose the right plant for the right spot
Great variability on plant size.
Ground covers to trees.
2. Don’t try to make a tree-type into a small shrub using radical pruning techniques.
3. When you prune, use selective thinning, or, remove entire branches/canes to the ground rather than heading back every year to the same (ugly) stubs.

42. Exceptions to the Rule:

43. Hydrangea problems

44. Special cases Hybrid Tea Roses Cut back to 8-18” in early spring.
Prefer cutting back to an outward facing bud.

45. Special Cases Hybrid Tea Roses Inward pointing bud
Outward pointing bud
Outward pointing bud

46. Pruned
Unpruned

47. Knock out Roses

48. Climbing Roses

49. Special Cases Ornamental Grasses
*Growing point for grasses is near the ground
*Annual shearing should be done before new growth begins in late winter/early spring.
*Large grasses like pampas and fountain grass we may only be able to cut back to 12-18”.

50. Ornamental Grasses

51. Bradford Pears
Excessive branching and shape makes them susceptible to storm damage.
Avoid topping
Thinning out branches is best way to prune
Know potential size!

52. Bradford Pears

53. Bradford Butchering

54. Prune only if you know why.

55. Plan expected outcomes

56. Correct problems while the plant is young.

57. Remove suckers and excessive water sprouts

58. Summary
Know when flowering plants bloom to determine timing of pruning.
Are they cane producing plants or not.
Evergreen plants grown just for foliage can be shaped at any time.
Severe pruning should be done in the spring for faster recovery.
Know rules for special cases.