Be judicious when pruning

Henry Kock is the opposite of the cranky gardener, the Interpretive Horticulturist at the University of Guelph Arboretum gets poetic about pruning.

I met a professional gardener recently who's gotten a tad cranky over the years. He doesn't like to be pestered with questions. When people ask him the best time to prune he says, "When you've got the time" and stomps off in a huff.

But he's got a point. If you pruned every plant when the books tell you, you'd start pruning in February and finish maybe in November. Better to keep it simple and prune RIGHT NOW! March and April are an ideal time to prune most of the plants in your garden.

Henry Kock is the opposite of the cranky gardener, the Interpretive Horticulturist at the University of Guelph Arboretum gets poetic about pruning.

"Let the plant tell you what might be needed. Express the plant as it is," Henry tells a group of skittish gardeners taking one of his popular pruning courses. Over four hours I sponged up the gospel according to Henry, and give just a few insights here.

The biggest sin is shearing or topping a tree or shrub. Shearing is the opposite of pruning, which is selective and thoughtful. In shearing you arbitrarily cut off every branch at the same height. This produces vigorous, weak growth called water sprouts. When you see a tree that has been sheared or topped it looks like Bart Simpson's hair. Not good. So the first thing Henry says is prune with an objective.

Maybe you want to rejuvenate an old lilac that's gotten as big as an America's Cup boat. A sensible plan would see you cutting one third of the oldest wood out over a three-year period. And when you cut it, cut it right down at the base of the plant, don't saw away halfway up the plant like a wimp.

Later in the season save your hand from carpal tunnel syndrome by refusing to pick off the spent lilac blossoms. Studies have shown it does nothing to improve the performance of the plant.

Most textbooks also advise gardeners to cut out deadwood and branches that cross. Always the thoughtful rebel, Henry challenges this thinking.

"What's wrong with dead wood? Trees have natural barriers that prevent the spread of decay." A few dead branches can be so important for wildlife, especially as habitat or "bed and breakfast" for predator and parasitic insects. So if the dead wood isn't hazardous (threatening to fall on the mailman) and doesn't offend neatniks and fussbudgets, leave it. Most pruning manifestos sternly advises you to prune spring flowering shrubs (forsythia, lilac, viburnum) after flowering. But if you are pruning and not shearing you won't lose that many flowers by doing it now, according to Henry. It is much easier to see into the shrub and make your cuts, before it leafs out and the branches are obscured.

When your jockeying around the interior of your shrub, make sure you make cuts in the right place, just above a bud or branch, and on a sloped angle. Remember if you prune above an outward facing bud, the new growth will face out, if you prune above an inward facing bud, the new growth will be directed inward.

Some pruning chores right now are mindless and pleasant. Parts of my boxwood are pale and anemic from winter damage. Every morning I do just a little trimming with bonsai scissors. Wow the effect is like Botox for boxwoods. Youthful vigor is being restored.

If you are out stomping around in your garden with sharp objects remember not to trample your wet ground too much, it destroys the structure of the soil. And consider cutting up all those prunings and scattering them underneath your trees and shrubs. Mimic what happens in the forest, where leaves and branches fall to the ground and decay. This builds up rich, humusy soil the kind of stuff that money can't buy.

Remember trees have survived for thousands of years by self-pruning. Don't be hasty, shadow someone who really knows how to prune, get a good book (I like the pruning guidebook put out by the Brooklyn Botanic Gardens, but it's hard to find, another good one is Rodale's Successful Organic Gardening Pruning) and don't forget the hardest thing is knowing when to put the pruning tools away.

For more information on pruning, and other gardening courses at the University of Guelph Arboretum: www.uoguelph.ca/arboretum/

The Arboretum University of Guelph Guelph, Ontario N1G 2W1 (519) 824 4120 ext 52113