Pruning is an important but generally poorly understood gardening practice. It=s one of those garden tasks (like pesticide application) which, if it=s not done the correct way at the right time, then is probably best not done at all. At the Botanical Garden we get questions about pruning all the time and people often say, AIt took x number of years to grow those branches and I just can=t cut them off.@ If done correctly, you won=t hurt the tree by pruning it, and you may be surprised how much better it looks and performs.
Ornamentals are pruned for any or all of the following reasons: to remove broken, dead or diseased branches; to encourage flower and fruit development; to control the size and shape of the plant; to maintain healthy trees and shrubs; to increase structural strength and to rejuvenate old flowering shrubs.
Follow guidelines
The following are some general guidelines as far as time to prune is concerned. Broken branches should be cut off immediately before they fall and damage the bark or other limbs. Trees and shrubs that bloom in the spring or early summer (Forsythia, Honeysuckle, Mountain Ash, Lilacs) should be pruned after flowering. Fruit-bearing trees and shrubs (Apple, Plum, Cherry, Currant) should be pruned in early spring before they bloom. Late flowering shrubs which flower on new growth (Shrubby Cinquefoil, Elderberry) should be pruned before active growth begins. Most evergreens are best pruned after the wood is thawed but before active growth begins. Pines are an exception and are pruned after the buds are extended (candled) but before the individual needles are fully formed. Take off only about half of the >candle= to avoid damage and poor formation of the new growth. Some trees bleed sap freely when pruned in the spring (Birch, Golden Chain, Poplar, Maple) and are better left until they are leafed out to
cut down on sap loss. Avoid late summer and early fall pruning because a new flush of growth encouraged by the pruning may not harden off and turn from >green to brown= before winter sets in. Late fall pruning can result in the wounds not healing until spring and cause dieback of the cut branches.
When you decide to prune a tree or shrub, look at the natural form or growth pattern. Try to enhance this look, not change it. Avoid the Ahaircut@ style of pruning where all branches are cut the same length. This is okay for some shrubs but tends to cause too much tip growth which can shade the centre of the plant and inhibit growth.
Your first cuts should remove all the dead, broken or diseased branches. This is good practice and it is hard to go wrong cutting. Using the proper tool for the size of the branch, cut back to the Acallus ring@ ( a circle of raised tissue around the base of the branch). Be careful not to damage this ring as it is the tissue that will eventually close over the wound. Don=t cut the branches off flush with the trunk, this makes for a larger wound and removes the callus. You can use a pruning paint if you want but this is more for looks than necessity.
Pruning provides light
Your next series of cuts will be to remove branches that are crossing over or rubbing each other. This is especially important in the centre of the specimen where too much material can cut down on sunlight and air reaching the crown of the plant and contribute to pest and disease problems. Next have a good look and remove weak or spindly branches. When shortening branches, make your cut about 1/4 inch above an outward facing bud at a 45-degree angle. This will keep the new growth going away from the crown, leaving the centre open.
Use three-cut method
When removing larger branches with a saw you will want to use the Ajump@ or three-cut method to avoid having the branch tear the bark along the trunk when it falls. Make the first cut from the bottom of the branch four to six inches away from the callus ring. Cut upwards until you get about a third of the way through. The second cut is made a couple of inches farther out and this one goes right through, removing the branch and letting it fall. The undercut keeps the falling branch from tearing the bark. Now that the weight of the branch has been removed, the final cut can be made back to the callus ring. Either support the branch stub when you cut it or cut through the bark from the bottom to avoid any tearing.
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