Most trees will grow perfectly well all by themselves without the interference of pruning. You stick them in the ground, water them and up they soar, seeking the light and the air as only trees can do.
In an urban setting, however, some tree varieties may very quickly outgrow their welcome. Some, like old-fashioned crab apple trees, will take over the entire backyard. You cannot sit comfortably in their shade because the branches are too low. You cannot walk under them without banging your head, yet most of the fruit is too high to pick unless you have a crane and a bucket lift.
Pruning makes the tree fit to your space, rather than the other way around and when a tree is properly trimmed it will allow in more light and may even produce a better harvest of fruit.
March is a good time to prune many deciduous trees, including fruit trees. The key is to prune the trees before they leaf out, before the sap starts running.
Elm trees are one exception. Open cuts to pruned branches could attract the beetles that carry the Dutch elm disease so pruning is only allowed on these trees between Oct. 1 and March 31.
Maple syrup
If you don't want to go into the business of making syrup, remember that birches, maples and walnut trees should not be pruned until the trees are fully leafed out. These trees have a powerfully strong hydraulic system of pumping the sap in the spring and if pruned too early, they could die.
"They will lose their sap once the tree does leaf out," said Ed Toop.
Toop, a retired University of Alberta horticulturist, now volunteers at the St. Albert Botanic Park and has taken on the job of tree pruning each spring.
As he walks down the park's rows of apple trees, Toop explains why it's important to prune every year.
"If you are doing a major pruning, don't prune back more than 1/3 of the tree. If you have a tree that's never been pruned, it gets to be a rat's nest of branches. It's easier to do a bit every year," he said.
Simply lopping the top of the tree of to make it shorter will cause the tree to grow more vigorous sprouts, so it ends up looking much like a hairy dog. But by slowly cutting back over several years, the tree may be trained and kept at a more desirable height.
"Instead of just chopping two feet off the top, only cut it back to where there's a strong lateral or side branch. You may be able to train that branch to become the new top," said Amanda Chedzoy of Tree Sense.
Eventually over a year or two of pruning sessions, the tree may be trimmed back from the new side branch so that the short height is maintained, she said.
The side shoots need to be kept trimmed off so that the tree has a stronger frame.
"The side shoots may be too small and may weaken the tree," she said.
No paint
In the old days tree wounds were treated with a dressing to prevent the sap from leaking. Arborists no longer follow that practice, Toop said, because the tree will heal itself.
"While dressings do protect against the invasion of water, pathogens and insects, they do slow down the healing process. Some horticulturists recommend that only cuts with a diameter of more than 15 centimetres should be dressed and then, use only recommended dressings. Do not use ordinary paints," he said.
Toop showed that cutting branches off tall trees can be strenuous work because it requires reaching and even climbing. For tall branches he uses an expandable rod pruning device that reaches at least 10 feet. For eye-level pruning he has hand-held secateurs for smaller branches and a pruning saw for larger branches.
"Use a proper pruning saw," he said. "If you try to use a regular saw on green wood, it binds and jams up. The teeth on a pruning saw are easier to work with."
Make all cuts close to and parallel to the trunk or crotch of a tree or close to an existing bud, which is facing in the direction that you wish the future shoot to grow. Cut branches that cross over each other or that compete for the same space within the crown of the tree. Cut out the dead limbs.
No stumps
Toop pointed to a ridge or collar that grows at the base of a branch where it connects to the trunk. This collar is the part of the tree that vigorously produces new cell growth and helps a tree to heal when it is cut.
"Cut the branch as close as possible to the trunk but avoid cutting into the collar or ridge. But at the same time, don't leave a stump. Cut if off because the stump will just rot and could cause disease," he said.
If a big branch is a problem because it hangs over your sidewalk or patio area, don't be afraid to cut it off. Removing a big branch will not harm the tree.
"Maybe it hurts them a bit, but they don't scream," Toop joked, as he suggested a three-step method for removing the big branches.
Make the first cut part way through the branch from the underside and a short distance from the trunk. Make the second cut from the top down, five to eight centimetres further out on the branch than the first cut. The weight of the branch will cause it to break free and fall outward without tearing any bark. The third and final cut is made close to the trunk so as not to leave a stub, he said.
"Pruning a tree will help it to develop a strong framework to withstand winds," Toop said. "It will revitalize an older tree because by pruning out part of the crown you reduce leaf area that the root system has to supply. This results in more vigorous growth in the remaining branches and it increases air circulation within the tree."
