Proper Pruning is part four of four in the Street Trees: Site Selection, Planting, and Maintenance in the Urban Landscape series.
Proper pruning will be an integral part of any successful urban forestry program. Without some form of help, trees seldom develop growth patterns that complement urban forest uses. Wide crotch angles, which provide strength, and strong central leaders are not normally the result of nature. For pruning to be beneficial, it must be done at the proper time of year and with a specific purpose in mind. For initial planting and establishment, all pruning and shaping should have been done at the nursery but, if pruning is required, wait until after the first season. Research indicates that pruning inhibits root growth. The first season’s priority is establishment. Maintenance pruning will be required on a regular 3- to 5-year cycle and should be planned for from the beginning.
Major pruning cuts should be performed from December to March in Alabama. Earlier pruning may initiate undesirable growth and later pruning may cause the tree to bleed severely (this is not necessarily detrimental to the tree). Injury to the tree, safety reasons, or pruning schedules may force you to prune at other times of the year. The risks and benefits of pruning out of season must be weighed and compared before a decision is made. Small pruning cuts (1- to 1½-inch diameter) can be made during any time of the year. Crossover branches, dead or dying limbs, water sprouts, and double leaders should be removed immediately to reduce possible injury to the tree. This is the only kind of pruning that should be performed at the time of establishment.
Excessive pruning stimulates suckers and water sprouts, which cause more pruning the following year. After the first year’s growth, further training cuts can be made. Ideally, trees should be trained with strong central leaders and wide crotch angles in the 10:00 or 2:00 position. The importance of establishing a strong growth habit cannot be overemphasized. Untrained trees may seem beautiful and full when young but may develop severe hazards and be predisposed to injury as they mature.
When pruning, the position and sequence of cuts is extremely important for larger limbs. Before making any removal cut, you should locate the branch bark ridge and branch collar. This will be the position of the final cut. Move up the limb approximately 6 inches and make a cut upwards one-fourth the diameter of the limb. Move an inch or so beyond this cut and cut down through the limb. This should leave a 7-inch stub. The final cut should be from the outer edge of the branch bark ridge through to the outer edge of the branch collar. Make the cut as smooth as possible. Pruning paint or sealer is not beneficial or recommended.
Remember the importance of pruning in your urban forestry program and be sure to practice it correctly. In review, the steps to successfully establishing street trees are as follows:
- Evaluate the site including consultation with the city engineer, create a design, select the species for the site, and plan the follow-up care.
- Create the proper environment for the plantings, select high-quality plants, implement the design, and plant no more than can be maintained properly. The guidance of an experienced professional may be needed and may prove cost-effective.
- If restoring or creating a pleasant, thriving, economically sound urban environment is one of your city’s goals, planting of trees and proper planting and maintenance of the urban landscape is not a frivolous beautification project. It is a necessity, and it requires the same planning and budgeting as sidewalks, lighting, buildings, and other city structures. Trees are a high-priority investment. Plan wisely, select carefully, and maintain your trees. The value will increase.
Street Trees: Site Selection, Planting, and Maintenance in the Urban Landscape series