Types of Pruning

The most common system used by Arborists is natural pruning. The goal is for the tree to remain in a more or less natural state while allowing for the tree's unique growth pattern and adaptations. There may also be alterations for clearance, view, aesthetics and structural improvement.  Overall general shape of tree is not altered in a major way, most Arborists would prefer that is a tree is pruned in a natural system.

Reduction pruning refers to reducing the crown or canopy size of a tree.  A typical reduction is measured by reducing  the percentage of the canopy by 1/3, 1/4 or 1/2. This is best accomplished by reducing limbs back to their point of origin or back to laterals capable of sustaining the remaining limb.  

Clearance pruning encompasses several methods.  

• Structural clearance: Removing any encroaching or hazardous limbs that are near or on a structure.
• Public clearance including roadways and sidewalks.  The owner of a lot  shall maintain any trees or other landscaping along the street or within the street right-of-way. Proper clearances are necessary to not interfere with the public convenience or safety in the use of the streets and sidewalks. There is a minimum eight-foot vertical pedestrian clearance from the top of the sidewalk and a minimum thirteen-foot vertical vehicular clearance from the top of the curb, to any part of a street tree. 
• Utility pruning: Removal of branches or stems to prevent the loss of service, damage to utility equipment and to allow for utility worker access. Power line clearance is a highly specialized type of Arboriculture with added risk and requires additional certification.

Pollarding, Espalier and Topiary are specialized forms of pruning.

• Pollarding: Severe heading followed by sprout removal annually or every few years to keep large growing trees to a modest size and maintain a formal shape.
• Espalier: Combination of pruning and training branches that are oriented on a specific plane including  a support wall, fence or trellis. This pattern can be simple or complex and is commonly used for fruit trees when space is extremely limited.
• Topiary: Maintain an artificial shape in individual plants or shrubs. Common topiary shapes include all types of hedges, geometric shapes and animals.

The goal is not to be aesthetically pleasing but rather to create a strong fruit-bearing structure that provides room for sunshine, air circulation and fruit production.  Long term strategy rather than a one time job and timing of the year is very important.  As a rule, growth is maximized if pruning is done just before the buds swell, in the late winter or early spring.  Pruning when trees are dominant can minimize the risk of pest problems associated with wound entry and allow trees to take advantage of the full growing season.  Best time of the year for pruning is mid December through March.

Vista pruning is a style used to enhance a specific view.