Pruning or Trimming
Pruning is the most common tree maintenance procedure. Although forest trees grow quite well with only nature’s pruning, landscape trees require a higher level of care to maintain their structural integrity and aesthetics. Pruning must be done with an understanding of tree biology. Improper pruning can create lasting damage or even shorten the tree’s life.
Reasons For Pruning
Because each cut has the potential to change the growth of the tree, no branch should be removed without a reason. Common reasons for pruning are to remove dead branches, to improve form, and to reduce risk. Trees may also be pruned to increase light and air penetration to the inside of the tree’s crown or to the landscape below. In most cases, mature trees are pruned as corrective or preventive measures, as routine thinning does not necessarily improve the health of a tree
When to Prune
Most routine pruning to remove weak, diseased, or dead limbs can be accomplished at any time during the year with little effect on the tree. As a rule, growth and wound closure are maximized if pruning takes place before the spring growth flush.
- Cleaning is the removal of dead, dying, diseased, weakly attached, and low-vigor branches from the crown of a tree.
- Thinning is selective branch removal to improve structure and to increase light penetration and air movement through the crown. Proper thinning opens the foliage of a tree, reduces weight on heavy limbs, and helps retain the tree’s natural shape.
- Raising removes the lower branches from a tree to provide clearance for buildings, vehicles, pedestrians, and vistas.
- Reduction reduces the size of a tree, often for utility line clearance. Reducing a tree’s height or spread is best accomplished by pruning back the leaders and branch terminals to secondary branches that are large enough to assume the terminal roles (at least one-third the diameter of the cut stem). Compared to topping, reduction helps maintain the form and structural integrity of the tree.