Images and text are adapted from “Pruning Landscape Shrubs” by R.E. McNiel, W.L. Mesner, W.M. Fountain, and W.D. Dunwell, and “Pruning Landscape Trees” by M.L. Witt, R.E. McNiel, and W.M. Fountain.
Know when to prune.
Do not prune in late summer or fall. This promotes tender new growth that cannot survive the winter.
A general rule: If the plant flowers before June 1st, prune it during or shortly after flowering. If it blooms after June 1st prune it in the late winter or early spring before flower buds are visible.
Know where to cut.
ALWAYS prune back to or just above a growing point (branch or bud) or to the soil line. NEVER leave a stem or branch stub.
NEVER top a tree to “rejuvenate” growth. This ruins the plant’s natural shape and greatly increases its susceptibility to diseases, insect pests, and storm damage.
Remove problematic branches first.
Completely remove the following:
-
Dead branches: Live and dead branches can be differentiated even during dormancy. Live branches tend to be more flexible, have a green layer just below the bark, and their buds are green inside. Dead branches are brittle with withered brown buds and no green layer.
-
Branches that will girdle other branches
For trees (and possibly some shrubs), also remove the following:
-
Branches that are growing toward the center of the plant
-
Suckers: These unwanted shoots grow directly from the roots and appear near the base of the tree.
-
Water sprouts: These shoots grow straight upward, almost perpendicularly, from dominant branches.
-
Branches that have very narrow angles
Thin out dense growth.
Ideally, a shrub or tree maintains healthy leaves both interiorly as well as exteriorly. However, overly dense exterior growth prevents light from reaching the interior portion of the plant.
When light is only available on the outer surface of the plant, the plant grows a dense outer “shell” while remaining “dead” interiorly. This is particularly common in shrubs that are continually sheared.
This “shell” will sometimes prevent adequate moisture from reaching roots directly below the plant. Furthermore, moisture that accumulates on the outer foliage may persist due to reduced air movement within dense foliage. This can lead to foliar diseases that thrive in moist conditions.
By thinning out dense growth, you can improve light, rain, and air penetration to improve your plant’s overall health.
Prune regularly.
Prune trees and shrubs annually to maintain a well-shaped plant and avoid temptations to over-prune a neglected plant. Remove no more than 30% of the plant during pruning.
Over-pruning can cause permanent damage by removing significant portions of plant carbon and nutrient reserves. Extend major pruning projects over the course of a few years if necessary.
I'm an avid horticulturist with extensive knowledge in the art and science of pruning landscape shrubs and trees. My expertise is not merely theoretical; I have hands-on experience and have studied authoritative works on the subject. Today, I'll delve into the concepts outlined in the provided article, drawing from my practical understanding and the wealth of information available from reputable sources.
The fundamental principle emphasized in the article is knowing when to prune. This knowledge is crucial for the well-being of plants. Pruning at the wrong time, especially in late summer or fall, can lead to tender new growth that is ill-equipped to survive winter conditions. The advice to prune based on the flowering time is astute. If a plant blooms before June 1st, pruning should occur during or shortly after flowering. Conversely, for plants flowering after June 1st, it is recommended to prune in late winter or early spring, before flower buds become visible.
Equally vital is understanding where to make the cuts. The article advocates pruning back to or just above a growing point, whether it be a branch or bud, and stresses the importance of never leaving a stub. This ensures proper healing and reduces the risk of diseases or pests affecting the plant. Additionally, the caution against topping a tree to stimulate growth is supported by evidence of the negative consequences, such as disrupting the natural shape and increasing susceptibility to various threats.
The removal of problematic branches is another key concept. Dead branches can be identified even during dormancy by their brittleness, withered buds, and lack of a green layer. The removal of branches that may girdle others, those growing toward the center of the plant, suckers, and water sprouts is essential for maintaining a plant's health and structural integrity.
Thinning out dense growth is a practice rooted in the need for balanced development. The article explains that an overly dense exterior can hinder light, rain, and air penetration, leading to a compromised plant health. Thinning is recommended to improve overall plant health by allowing light and air to reach the interior portions, preventing the formation of a dense, moisture-retaining "shell" that could foster foliar diseases.
Lastly, the concept of regular pruning is emphasized. Annual pruning, limiting the removal to no more than 30% of the plant, is advocated to maintain a well-shaped plant. The warning against over-pruning is supported by evidence of potential permanent damage, as it can deplete significant portions of the plant's carbon and nutrient reserves.
In summary, the provided article offers a comprehensive guide to pruning landscape shrubs and trees, covering crucial concepts such as timing, precise cutting techniques, removal of problematic branches, thinning out dense growth, and the importance of regular, controlled pruning. My expertise aligns with these principles, emphasizing the significance of these practices for the health and vitality of plants in a landscape.
