Did you know that many structural defects that occur in older trees are preventable? Pruning trees when they are young helps ensure a strong and more structurally stable form as the tree grows. We call this practice structural pruning. It helps mitigate the need for more expensive tree care practices later in the life of the plant and can extend the lifespan of the tree by decreasing the likelihood of branch failures.
Growing Conditions: Forests vs. Landscapes
Structural pruning of young, developing trees provides a desirable and stable form at maturity and is one of the best investments you can make in your landscape.
Forest trees tend to develop a sound structure in response to competition from other trees. Growing in the developing forest canopy suppresses growth of large, lower limbs. Dominant forest trees tend to maintain a single stem and narrow crown as they grow toward light. This produces a reasonably strong structure in mature forest trees.
Conditions are radically different, however, when you plant trees in a landscape. Exposed to full sun, trees will grow with a broader, more complex crown than those in the forest. Lower branches may grow very large, limbs develop in close proximity to one another and multiple stems can develop. Certain species such as maple, elm, ash and dogwood are particularly prone to developing structural defects that increase the likelihood of branch failures. As trees mature and grow large, correcting these issues (if they can even be corrected) becomes more expensive.
Start Structural Pruning Early
When trees are young and small, it is much easier and less expensive to undertake pruning that encourages the development of a strong form. Frequent assessment helps determine when pruning is needed to maintain structure and correct any deficiencies. On some species, you may need to schedule pruning as frequently as every two to three years for the first 10-to-15 years after planting.
During these years, an arborist prunes trees to maintain a single dominant stem unless multiple stems are specifically desired (for species such as birch or crape myrtle). The arborist will prune branches so their size remains proportional to the stem diameter at their point of attachment. He or show will also remove some branches as the tree grows to ensure adequate spacing between permanent scaffold limbs. The shape of the tree is maintained to provide a natural open grown form typical of the species.