B.3.6.1.5 Tree And Shrub Pruning

Scope

This guide is intended to be used by those having little or no knowledge or experience in the field of tree and shrub pruning.  It is a source of basic pruning information only, and by no means a complete or comprehensive manual. 

References

The Directorate of Environmental Compliance and Management (DECAM) Natural Resources Division, Agronomy section and the Colorado Springs City Forestry.  For additional information, access the Colorado State University Cooperative Extension web site called Planttalk Colorado® at www.colostate.edu/Depts/CoopExt/PTLK/ptlkmenu.html or by phone at 1-888-666-3063. 

Reasons To Prune

There are lots of reasons that trees and shrubs are pruned.  Some examples include: 

  • To provide clearance for pedestrians, vehicles, signs or utility lines. 

  • To improve the plant's appearance. 

  • To remove dead, broken, diseased or potentially hazardous branches. 

  • To “train” a plant and promote strong, healthy development.  

Pruning Standards For Trees: 

  • Make sure you have the proper tools before starting any work (see paragraph 7).  All tools used to make cuts should be sharp and in good condition. 

  • All cuts made to the tree should be just outside the branch collar.  The branch collar is the “shoulder” area where a branch joins another branch or trunk by overlapping xylem tissues.  There should be no stubs remaining or flush cuts made as a result of the pruning activities. 

  • When branches are pruned back to a side limb, that remaining limb must be at least one-third the diameter of the branch removed. 

  • When removing heavier branches, do not allow the bark to tear.  Tearing can be avoided by using the three cut or `stub cut' method.  Make the first cut 1/3 of the way through the limb on the underside, beyond the area of the final cut.  Make the second cut from the top down to remove the limb.  Make the third cut just outside the branch collar (see 4.2 above) to remove the remaining stub.  

  • Remove no more than 30% of the live wood from a tree, unless safety conditions dictate otherwise.  As much live wood as possible should be left in the tree. 

  • Pruning work should be confined to that which can be accomplished while working on the ground or off of an approved stepladder or with a pole-pruning tool.  Trees should not be climbed. 

  • Do not use power saws (chainsaws). 

  • Care should be taken not to nick or scar stems or branches, especially on thin barked trees such as Linden, Honeylocust or Crabapple. 

  • Do not attempt to reduce the height of a tree without first contacting the DECAM Agronomy Branch for approval.   

  • There shall be no topping of trees.  Topping trees involves removing the crown all the way back to the main or lateral branches.  Topping results in sprout production from the cut ends that become hazardous once the sprouts become large and heavy.  Topping may also result in the death of the tree due to so much of the crown being removed the tree cannot make enough energy to survive.  Insects and disease will also spread through the cut ends.  Topped trees are disfigured trees and reduce the value of the overall landscape. 

  • All pruning should be done in a manner that maintains the natural symmetry of the particular tree being pruned. 

  • Tools used to work on diseased trees should be disinfected between each cut and after completion of work.  Disinfecting may be accomplished by applying Lysol, isopropyl alcohol or similar material.

Timing Of Pruning

  • Most tree species may be pruned at any time of the year, however, there are some exceptions: 

  • American Elm and all fruit trees should be pruned only when dormant (winter/late fall/ early spring).  This is because many of the diseases that affect these species of trees are active during the growing season.

  • Maple trees should be pruned only while in leaf in order to minimize "bleeding". 

Pruning Standards For Shrubs

Many of the standard pruning methods mentioned above also applies to shrubs.  Specific guidelines to follow when pruning shrubs include: 

  • Twigs should be pruned back to buds or branches going in the desired direction.  Cuts should be made slanting in a parallel direction of the desired stem or bud and should not be too close or far away from the bud. 

  • All diseased, dead, weak or broken branches should be removed. 

  • Branches, shoots or twigs that are growing in the wrong direction, distorting shape, or crossing over others should be pruned back or removed. 

  • Shrubs with multiple stems should be thinned out while maintaining the shrub's natural shape.  Remove approximately 20% to 30% of all stems to ground level. 

  • Deciduous shrubs (those that lose their leaves in the Fall) that are too tall and are lacking foliage on the bottom part of the shrub can usually be cut to ground level and allowed to regenerate and form a "new" shrub. 

  • Shrubbery should not be sheared unless it has already been maintained that way.  (Note: it requires more maintenance to keep a sheared shrub looking good than it does a pruned one.)  In most cases, plants should be sheared so the top is narrower than the base.  This prevents "legginess" caused by the top branches shading out the bottom ones.  Exceptions should be those plants already sheared into a different shape (i.e. round), in which case that shape should be maintained. 

Suggested Tools: 

  • Bypass or scissors-type hand pruners. 

  • Bypass or scissors-type loppers. 

  • Anvil-type loppers. 

  • Hedge shears. 

  • Small hand saw. 

  • Large hand saw. 

  • Pole pruner. 

  • Pole saw. 

  • Leaf rake.

  • Broom.

 

  
 

Appendix b