Portland Landscape Design and Tree Care Service

Pruning advice - Part 1

Copyright 2005 - 2011 by M. D. Vaden. Pruning information is divided into Part 1, Part 2, Part 3, Etc. - plus other pruning topics.


Pruning Part 1

The information below is a most basic pruning guide to avoid pruning the wrong way once you have pruning equipment in hand. There are reams of great pruning advice already online and in books. I wrote the brief pruning information because some pruning guides won't mention some of the tips. A pruning schedule for some shrubs is included. Consult several articles and pruning books. The more tips you learn the better.

Reasons for pruning include safety, health, aesthetics, access and scenic views. Pruning can increase fruit production, and the value of timber by improving wood quality. Proper pruning involves removing little defects before they grow into big problems. And in my experience, leaving plants to themselves like nature is unwise. When you hike in the woods, what you see are the survivors, not the ones that split, broke and died. That's why nature puts decay fungi to work too. In a garden or urban setting, we want a high rate of survival, and pruning helps meet that desire.

Pruning for safety involves removing branches that could cause injury or damage, trimming branches that interfere with visual safety at driveways, and pruning away branches that grow into utility lines (pros). Pruning for health involves removing diseased or insect-infested wood, thinning the crown to increase airflow, and removing crossing and rubbing branches. Pruning can best be used to encourage and develop a strong structure and reduce the likelihood of damage during severe weather.

pruning roses with pruning saw or secateurs

Removing broken or damaged limbs encourages wound closure, because the useless parts won't remain in the way of the tissue that's trying to close-over the wound. One more reason not to leave the plant to itself like in a natural woodland.

Proper pruning is accomplished much easier with the right pruning tool for the job. Review selecting pruning tools.

When deadwood and excess branches are thinned from inside the canopy, more filtered light can penetrate the canopy. This allows light to reach perimeter foliage in a back-lit fashion.

The remaining foliage will benefit from the extra light. If understory plants are under the main foliage canopy, those will acquire more light also. Pruning for aesthetics involves enhancing the natural form and character of plants or stimulating flower production.

Most woody plants shed foliage and branches in response to shading and competition with other shrubs, hardwoods and conifers.

After branches fall, the openings are sealed by woundwood (callus). Branches that are poorly attached may be broken off by wind, accumulation of snow and ice or even animals like raccoons.

Branches that don't produce enough carbohydrates from photosynthesis will die and are eventually shed by decomposing and falling off. If those limbs are large enough, a hazard may result. Later, visit our page with photos and information about Signs of Hazards

Even accumulated water weight from winter rain can bring big branches down. Branches removed by natural forces often get ragged wounds that don't seal or naturally compartmentalize with new tissue. Pruning can supercede and replace these natural processes and increase the strength and longevity of plants. Nature does not prune or care for plants to meet the needs of people. We need to prune to meet personal needs and reduce hazards. And keep in control of the growth.

Proper prunng means canopies can be shifted and directed very effectively. By removing leaders growing toward a building, and leaving other main stems, the form can be directed away from the structure. This is why nature should not be replicated in all ways at all times.

pruning guide and tips

Plants that stand alone and can grow outward in all directions are often a bit easier to prune. One specimen like that is this Mt. Fuji Flowering Cherry.

Woody plants in a natural environment like a forest, are not directed in a way that pruning can offer. In a forest, plants will bend and grow toward light a little. Thats due to plant cells elongating on the dark side of the stem and "pushing" the plant toward light.

In this diagram, blue higlights indicate branches that could be removed to provide an adequate crown thinning. It takes some thought, but the simplicity of bicycle spokes can be a good example to think about. Spokes are evenly spaced, radiating outward. The difference with a tree, is that the growth is not as perfectly arranged as wheel spokes.

Also, branches radiate outward and upward. But the concept is applicable. We don't want a bunch of criss-crossing branches. A woody plant needs pruning to remain somewhat orderly and organized.

Woody plants with pyramidal crowns like many conifers or evergreens, have a strong central stem and lateral side branches that are more horizontal, and do not compete with the central stem or trunk for dominance. With spherical crowns, like many hardwoods, lateral branches may compete for dominance more. Look at some maples for example, which have several leaders and large limbs all reaching upward in different directions.

To reduce the frequency of pruning, its best to consider the natural form of plants for planting and pruning care. It is very difficult to impose an unnatural form on a woody plant without an increase to maintenance. The more we fight nature, the greater our pruning workload.