EDMONTON -- Do not be afraid. Pruning a tree only sounds scary, Brendan Casement says soothingly.
Some people worry they'll damage a tree permanently by taking off too many branches, but the chances of botching the job are slim, unless you give it a severe brush cut, explains the retired horticulturalist, who teaches pruning courses at the Devonian Botanic Garden and at large garden centres in the metro area. People tend to cut the tops off trees when they've grown too tall.
"I think in many cases they made a mistake in their original choice of tree, choosing a fast-growing tree like a poplar when they should have been looking at, say, a mountain ash that's not going to grow as tall," he says.
The key to pruning your own trees is to take off no more than a quarter of the growth at one time each year. In other words, to the untrained eye, the "after" picture shouldn't look much different than the "before" picture.
So if your tree is older and has never been pruned, it could take six to eight years of patient pruning to get it in shape, Casement says.
Pruning too much at once encourages the growth of long whippy branches that don't strengthen properly, Casement explains.
He breaks the no-more-than-a-quarter rule when pruning his own fruit trees to keep them to a height of six feet, so he can continue picking apples without a ladder, he says.
Casement chuckles that the neighbours tell him his pruning is ugly, but it's ugly only because the trees hadn't been pruned for 20 years before he got his hands on them, which makes them harder to train.
The point of pruning is to maintain a tree's health. If you never prune, it will likely shorten the life of the tree somewhat.
"We like to say you train a young tree and then prune to maintain the health of an older tree," Casement says.
A pruner's targets are branches that rub against each other or cross each other; branches that are more vertical (70-degree angle) than horizontal (45-degree angle), as the more vertical branches tend to be weaker; and water sprouts -- long whiplike branches that grow upright with few leaves at the top, which thicken the inside of a tree and prevemt the movement of air.
Low-hanging branches that prevent a person from cutting the grass beneath a tree and dead and diseased branches and suckers that come out from the ground at the base of the trunk should also be removed.
Some trees can be pruned year round, as long as it's not too cold. "Too cold -- below minus 17 C -- is bad for people, bad for trees and bad for the equipment you use to prune," Casement says.
Early pruning, as in early to mid winter is OK for trees with thicker bark such as poplars. Late winter pruning, in March and April, is better for thinner-bark trees such as mountain ash, Casement says.
Ideally mountain ash and chokecherry trees should be pruned before buds start to appear.
Birches can be pruned after leaves appear.
There is a ban on pruning elm trees from March 31 to October 1, to prevent the spread of Dutch elm disease, Casement explains.
Although the average homeowner can prune his or her own trees, if you're really nervous about it, or the tree is older and quite large, it's probably a better idea to bring in professionals with the right equipment to do the job safely, he says.
-- Canwest News Service
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