Trimming a tree is all about managing size, right? Yes, controlling size is a normal and common reason for trimming or pruning a tree. However, there are three additional reasons trees should be trimmed. Trimming a tree stimulates its growth, trains its shape and appearance, and promotes its vitality.
Trimming Promotes Vitality
Dead, diseased, or redundant branches are important to remove for the sake of the tree’s health. This is called crown cleaning.
Removing a diseased branch eliminates the threat of the disease spreading to other parts of the tree. Removing a redundant branch (i.e. a twin or parallel branch that does not contribute to the tree’s structure) frees up nutrients and allows those to distribute to other branches. Removing a dead branch eliminates the possibility of it snapping off and breaking healthy branches on its fall to the ground.
Crossed branches, water sprouts, and suckers should also be pruned out. The latter consume water and valuable nutrients and detract from the tree’s appearance and integrity. Crossed branches can introduce disease to the tree if the intersection becomes rubbed open and bacteria enters the wound.
In a densely branched tree, it can be beneficial to prune out some of the interior branches to allow light and air into the center of the tree. This treatment is called crown thinning.
Trimming For Shape and Appearance
Most arborists recommend letting trees grow into their natural shape, size and form. One exception is specialty trees or trees with uniquely decorative functions.
Topiaries are trees that are intentionally pruned into specific forms: stacks of spheres or other geometric shapes, animals at parks, or cartoon characters at theme parks.
Espaliered trees are pruned to grow along a vertical plane such as a wall or a fence. Espaliered trees are usually fruit trees, and this method of trained growth optimizes vertical plane space and makes it easy to pick ripened fruit.
Trees that are espaliered can be purely ornamental and can be deciduous or evergreen. Their branches are often pruned into perfectly symmetrical shapes, for example a Y, where the bottom of the Y is the trunk and the arms of the Y are branches. Other common espaliered shapes are fans, candelabras, lattices, or cordons. This last shape is where the horizontal branches grow straight out from the trunk and occur in evenly spaced pairs.
Trimming Stimulates Growth
Counter-intuitively, cutting a branch back usually results in new growth with thicker foliage because multiple leaf buds form at the trimmed branch tips.
Dying and diseased branches that are trimmed out result in nutrients directed into healthy branches.
Most trees benefit from a regular trimming or pruning. If you are a homeowner without the help of a landscape/tree-trimming service, make sure you have the right tools and information for the job. If you have large trees (anything over 12 feet), hire a proven professional to do the work. They’ll do the job in a quarter of the time that it would take you and the tree will be done properly and safely.