Useful Information

Pruning Standards

With the American National Standard for pruning, ANSI A300, specifications can be written in a virtual infinite number of combinations. The following information is designed to help you understand exactly what will be accomplished in a pruning operation.

  • Branch Size – A minimum or maximum diameter size of branches to be removed should be specified.  This establishes how much pruning is to be done.
  • Pruning Objectives – Pruning objectives should be established prior to beginning any pruning operation.
  • Hazard Reduction Pruning – Hazard reduction pruning (HRP) is recommended when the primary objective is to reduce the danger to a specific target caused by visibly defined hazards in a tree.  For example HRP may be the primary objective if a tree has many dead limbs over a park bench.
  • Maintenance Pruning – Maintenance pruning (MP) is recommended when the primary objective is to maintain or improve tree health and structure, and includes hazard reduction pruning.  An example here might be to perform a MP operation in a front yard tree.

Pruning Types

Hazard reduction pruning and maintenance pruning should consist of one or more of the pruning types noted below.

  • Crown cleaning – Crown cleaning shall consist of the selective removal of one or more of the following items: dead, dying, or diseased branches, weak branches, and watersprouts.
  • Crown thinning – Crown thinning shall consist of the selective removal of branches to increase light penetration, air movement, and reduce weight.
  • Crown raising – Crown raising shall consist of the of the removal of the lower branches of a tree to provide clearance.
  • Crown Reduction, of Crown Shaping – Crown Reduction decreases the height and/or spread of a tree.  Consideration should be given to the ability of a species to sustain this type of pruning.
  • Vista Pruning – Vista Pruning is selective thinning of framework limbs or specific areas of the crown to allow a view of an object from a predetermined point.
  • Crown Restoration – Crown Restoration pruning should improve the structure, form and appearance of trees which have been severely headed, vandalized, or storm damaged.