February 9, 2013
Have you ever seen master pruners at work? It appears as if they're in a trance, completely in the moment, having a deep connection with their subject. This is not, unfortunately, what most trees and shrubs encounter when the "mow, blow and go" team swings in with their hedge trimmers.
Aesthetic pruning, or natural pruning, respects the natural shape, form and silhouette of the plants. It takes more awareness and effort than just hedging plants into little cubes and spheres.
Pruning trees and shrubs can be a very grounding and rewarding endeavor. It can also be great exercise. Pruning allows us to be creative and good land stewards. The overall attitude the pruner should take is one of respect and of inquiry. Since form always follows function, assuming the right plant was planted in the space, the landscape function of the plant coupled with its phenotype will determine the pruning strategy.
When approaching a shrub or tree to prune, first assess its overall health, noting why it's there in the first place, and determine if there are any main issues to address. Don't ponder for long. There are several steps to go through before the "aesthetic" part. The next step is to remove "The Three D's — dead, diseased and damaged wood."
When making a cut, it is important to follow the guidelines that limit the possibility of harming the plant while maximizing the capability of the plant to seal off the wound and put up natural barriers to infection. The main cuts to use are the three-saw cut, the heading-back cut, and the thinning cut.
The three-saw cut is a cutting procedure that protects a larger limb from ripping the bark down good wood and creating a larger wound. It involves making an under-cut first away from the branch bark collar, a second, top-cut just beyond the under-cut, allowing the heavier wood to break away safely, and a final cut at the growth ring. This cut encourages the plant to quickly seal off the wound with a callous roll initiated from the cambium layer under the bark.
The heading-back cut is one that reduces the length or height of a branch by cutting back to a smaller lateral or a bud. It is a directional cut that determines which way the plant will grow in the future. A good rule of thumb is that the smaller lateral cut back to should be at least one-third the size of what is being cut. Never remove more than one quarter of the green leaves of any plant during the growing season.
The other cut, the thinning cut, is one where an entire branch is removed at its place of origin; the growth ring. Never leave stubs or spikes, and don't make a flush cut. Stubs and spikes are hard for the plant to seal and flush cuts open up good wood to insects and fungal infection.
The next things to cut off are at the bottom — suckers. These may originate from the roots, below a graft, or from the crown of the plant. Following that, midway up, are water sprouts. These branches go straight up and usually cause rubbing branches that inhibit sunlight and air circulation in the plant. Sometimes, these can be left and headed back to fill in an empty space.
The last thing to remove is near the top: double leaders. While it is desirable for some plants to bush out and have multiple leaders, these should be broad, strong crotches. The narrow ones most trees create can cause problems in the future.
After removing all of these, it is time to look at function and aesthetics. Sometimes the function of the pruning is to make plants look older than their years. Sometimes it is to promote flower or fruit production in the coming season. Sometimes it is to create privacy, and other times it is to develop a strong structure for future growth, or just to keep the plant out of traffic. Try to achieve a natural symmetry and good branch spacing for ample airflow and sunlight.
It is important to consider how plants respond to being cut. If the growing tips of the plant are removed, the lateral buds and branches below it will grow more vigorously. Use this understanding to direct future growth.
To learn more about natural, aesthetic pruning, come see a Feb. 9 demonstration by Peter Churgel at Falkirk Cultural Center in San Rafael.