Why do we prune?
Manage growth Correct structural problems while the tree or shrub is small. Aesthetic beauty Because it is fun!
Types of Pruning
Thinning - the act of removing competing foliage within the crown of a tree or shrub to improve air flow, improve looks and to enhance structure. This type of pruning has many applications.
Reduction pruning - A very useful tool in keeping trees and shrubs small(er). Larger trees with defects such as decay, weak crotches, etc can be preserved by making them shorter and less of a target to wind. Many trees are removed by tree companies which could have been given a longer lease on life by reduction pruning . Reduction pruning relies on cutting branches back to natural growing points and is NOT tree topping.
Structural pruning - Many structural problems trees encounter could be avoided if the branching structure is pruned while the tree is small. Co-dominate stems with sharp angled crotches or "forks" can be the "weak link in the chain" resulting in breakage in storms.
Clouding - a type of thinning whereby openings are made to allow sunlight to reach inside the plant a to encourage inside growth. This is how boxwoods should be pruned.
Shearing - Reserved for shrubs - where by the outside foliage is cut along an even plane. I often see Large hollies and hemlocks at the corners of houses which are sheared. These become a maintenance nightmare as the act of shearing stimulates new growth immediately.
Natural pruning - a form of reduction pruning whereby leaders are pruned back to a natural growing points. The plant looks more natural and rapid regrowth is not stimulated as with shearing.
Deadwood removal - Once a limb, branch or any part of a tree or shrub dies, the plant is through with it. Removal of deadwood makes trees and shrubs much more attractive. As an act of sanitation , it is also a good practice.
Tree Topping - a very poor practice which should be avoided if at all possible. Topping messes up the metabolism of trees resulting in rapid regrowth , causes massive root death and opens the door to potential future structural problems. Topping creates trees with un-natural ugly crowns. One could argue that this is a form of reduction pruning with the same effects as shearing . Trees are not shrubs! However, there are cases in storm damage repair whereby topping cuts would be a good option in restoring a damaged crown.