Maintenance V: Pruning Techniques
Pruning requirements vary from plant to plant, but generally some types of wood need regular attention. Dead, dying, diseased, or damaged wood should be a priority. Prune dead twigs or branches, as these do nothing for the plant. Also, branches that are rubbing against each other should be trimmed. Such branches should be removed by cutting them right back to healthy wood. Branches along the lower trunk of trees should be allowed to grow for at least two years before removal because they encourage strong trunk growth, and protect the tree from sunburn and reduced wind resistance. When pruning trees, retain the strongest branches and remove damaged, weak, crossed, or narrow angled branches. Also remove shoots growing from the ground or base of the plant (known as suckers). Remember that trees should never be stubbed (to cut off or remove the top of the tree) since that will greatly impede their vertical growth. Most trees and evergreen shrubs often do not require further attention unless the shape or size needs to be altered.
Deciduous shrubs, however, often require additional pruning. Pruning helps rejuvenate older shrubs that no longer flower well. To encourage the production of flowering shoots, remove dead, diseased shoots, and shoots that go across the center of the shrub, and then cut all those shoots that produced flowers in the previous season to just above the bud. Where pruning is needed to encourage dense growth, trim off a terminal bud - a process known as pinching. This will encourage lateral branches to sprout, thus promoting the development of a bushier, more compact shrub. Many shrubs eventually will send up long shoots (this is called getting “leggy”). Such leggy growth needs to be removed to ensure uniform plant growth. If the plant starts to look too thin and woody, trim it back about a third to a half of its original height. If you ever are in doubt about what to remove, don’t remove it. When carrying out shearing or hedging for shrubs, keep the bottom of the shrub wider in diameter than the top, and thin out some of the branches. This allows greater sunlight to penetrate and encourages internal leaf growth.
Shrubs sometimes are broken or are permanently bent as a result of snow weighing down on the branches. In this case, broken or damaged stems should be cut back into sound wood, preferably back to a branch junction or where the stem joins another shoot. The stems that were pulled out of shape may be returned to their former position by tying them in, either to a stake, or to other branches.
Always make sure that your pruning tools are clean. This can be achieved by dipping them in a 10% bleach/water solution between cuts to avoid spreading disease. Also, keep your tools sharp, so they can make a nice cut – normally a slanted cut, at about a 45-degree angle, and above the bud. Always make smooth cuts and avoid crushing plant tissues. When pruning branches that are more than 2.5 cm thick, use a pruning saw.
This article is part of a series of articles prepared by the Center for the Study of the Built Environment (CSBE) on water conserving landscapes.
For additional information on water conserving gardens, visit the CSBE web site at www.csbe.org
Support for the CSBE project on water conserving landscapes is provided by WEPIA (Water Efficiency and Public Information for Action), a program being implemented in collaboration with the Ministry of Water and Irrigation and funded by the United States Agency for International Development (USAID).