page 94

pruning- removal of plant parts, branches, shoot tips, buds, roots, etc.

dehorning - heavy drastic pruning of large limbs; should be avoided at all times;
                 - Sometimes called "crepe murder"; repeat offenders

                   Also called pollarding. It is a pruning techniques used in some European cities.

thinning out - removal of branches back to their point of origin.
    Used to:

    1) decrease density of the canopy
    2) encourage other branches to grow and rejuvenate plant 
    3) redirect growth
    Result: less shade and allows lawn and plants to grow underneath the tree, example

heading back - removal of the terminal portions of a branch.
    Used to:

    1) increase density of the canopy
    2) encourage branching
    Result: create shrubs and privacy screens

     thinning out versus heading back - see next page

pinching - removal of the young, succulent tips of shoots.

hedging - removal of growth flushes on hedges or shrubs to shape canopy and induce
                dense growth.

disbudding - removal of excessive flower buds on flowering pot plants. Aggie Football Mum

root pruning - pruning of roots, usually with a shovel, to prepare plants for transplanting.
1) Health and safety

2) Maintain desired form

3) Dwarfing

4) Invigoration

5) Increase productivity of fruit - open center peach, grapes trellis

6) Equalize root/shoot ratio

7) Develop strong branch framework

page 94b
Thinning Out Versus Heading Back
(original tree image modified from Yard and Garden Brief, U. of Minnesota
tree before pruning 
Original Tree
The two basic types of pruning cuts are thinning out and heading back.  Each produces a distinctively different growth pattern.  In practice, a combination of the two methods are used.  That is, some limbs may be thinned out, while some of the remaining limbs may be headed back.  This allows one to prune a plant to achieve what ever shape and form is desired.
Thinning Out
(animated version)
thinning out cuts
Location of thinning out cuts
The cut is made at the point of origin of the branch.
thinning out after cuts
Tree Pruned by thinning out
Entire branches are  removed back to their point of origin.
thinning out tree 1 yr later
1 Year Later
The remaining branches grow more vigorously.  The tree develops a more open canopy with excellent light penetration to the interior branches and grasses and ground cover below.  On fruit trees, fruit production in the interior  would be promoted..
This is how one would prune a shade tree (oak, maple, ash) or some fruit trees (pear). 
Heading Back
(animated version)
heading back cuts
Location of heading back cuts
The cut is made above the point of origin of the branch.
heading back after cuts
Tree Pruned by heading back
The terminal ends of the branches are removed.
heading back 1 yr later
1 Year Later
Because apical dominance is removed, several lateral buds just below the cut break dormancy and grow into branches.  Thus, many smaller branches develop and the tree develops a more dense canopy.  The more heavily the plant is headed back the more dense the canopy will become.  Avoid heading back so heavily that the tree is dehorned, pollarded or topped, which is never recommended..
This is how one would prune a small tree for a dense canopy effect (plantanus) or tree form shrubs (crape myrtle, ligustrum, holly)

page 95

topiary - pruning to produce a 3-dimensional design or form. Disney World

espalier - pruning to produce a 2-dimensional design or form.

wide crotch
Wide (Y) Crotch Angle
very strong, select for when pruning
narrow crotch
                          angle with bark inclusion 
Narrow (V) Crotch Angle
with bark inclusion
200 year old pecan tree finally fails

very weak, selectively prune-out

                  pruning by Shigo

1 cut
                        incorrect pruning bark tear
incorrect method
target pruning 3
                          cut wide crotch angle 
correct method for
wide crotch angle
target pruning 3
                          cut narrow crotch angle 
correct method for
narrow crotch angle

page 96
1) Growth State: best when inactive or dormant

2) Susceptibility to winter injury: for plants easily damaged by winter freezes

  • prune after cold of winter  
  • remove all winter killed tissue
  • you may need to allow some spring growth to tell if tissue is dead or not.  
3) Time of flower bud formation on flowering plants:
    a) spring flowering plants:
    • flower on last years growth (2 year old wood); i.e. flower buds present since last summer or fall.
    • therefore, prune right after flowering in spring and before new buds form.  

    b) summer or fall flowering plants:

    • flower on current years growth (1 year old wood); i.e. flower buds form on new growth of current year.  
    • therefore, prune fall, winter or early spring, but best to prune after cold of winter and before new growth starts in spring.  
4) Transplanting: pruning should be to equalize root/shoot ratio, thus, decrease transplanting shock.
                           Where are the roots on a tree?
    How to equalize root/shoot ratio:
    a) thin-out immediately after or at the time of transplanting 
    b) root prune before transplanting (months to years). 

Chemicals that selectively kill or disrupt shoot tips to remove apical dominance. 
1) Atrinal 
2) Off-Shoot-0 
3) Maleic hydrazide 
4) Emgard 2007