Could we please, please adopt a mantra to be slavishly repeated before putting hand to loppers? I wish all would-be tree pruners would pledge allegiance to the Hippocratic oath taken by generations of medical students: "First, do no harm."
It turns out that the oath doesn't actually include these words, but Hippocrates apparently did write the phrase that captures the practical practice of pruning as well as the ethical practice of medicine. If we could just begin every pruning project with the goal of not inflicting damage, our gardens would be far more graceful. And we won't suffer so dreadfully from the sight of mal-pruned stubs sticking out of what used to be trees.
What causes such butchery? Is it a need for control? The poor tree is simply striving to fulfill its genetic heritage to grow and spread. If there isn't room for it to do that, it means the tree has been planted in the wrong place. It is a tree, not a shrub or a poodle or whatever it is people try to make trees into. If all this sounds harsh, it is because I recently walked through Volunteer Park admiring glorious full-grown trees, then took a good look around my neighborhood. What I see are trees cut off heedlessly, so that they grow as if tormented. What's especially weird is that the suckers at the base of the tree are often left to grow lustily, while the branches are hacked back into stubs.
Whenever I need to know anything about pruning, I call up Cass Turnbull, the mother of all pruning, and founder of Plant Amnesty. No one explains pruning more colorfully or knowledgeably. She reminds me that we're not just talking about aesthetics here; responsible pruning maintains the long-term health of the tree as well as its beauty. It also maintains the mental health of the gardener, because over-pruning results in maintenance nightmares. When you clip a tree into an ultra-tidy shape of your own devising, you'll end up with an ultra-mess later on. The bottom line is you can't control shape or size by pruning, because when you cut a tree it goes into a spasm of regrowth. You've simply sped up what you're trying to stop. Not all pruning is bad. Turnbull advises cutting out any dead wood, then, over time, removing any low limbs that get in the way. It is important never to cut more than an eighth of a tree's total foliage in any one year.
Recent research shows the error of the old belief that, to balance top growth and root mass, a tree should be cut back when first planted. Now we know that root growth and tree health are hurt by such early pruning and — back to the aesthetics — the tree may never recover its natural shape. When branches are cut back, the tree loses the leaves it needs for photosynthesis. Plus, if you refrain from clipping at planting time, the tree may appear dormant for awhile, but only because it is absorbed in the necessary task of developing a sturdy root structure.
Perhaps the best thing to do is relax and enjoy the fact that this is one of those rare instances in life, and in gardening, where virtue lies in doing less. Plenty of help is available to encourage you in this attitude. Plant Amnesty has a series of low-cost pruning classes ($3 for two hours!), plus handouts, videos, a referral service to expert pruners, and an Adopt-A-Plant service for plants that have outgrown their space. Contact Plant Amnesty by calling 206-783-9813, or going on the Web to www.plantamnesty.org. Turnbull has written a new book on pruning, due out in the autumn from Sasquatch Books. In the meantime, "The American Horticultural Society Pruning and Training: A Fully Illustrated Plant-by-Plant Manual" by Christopher Brickell and David Joyce (DK Publishing, 1996, $34.95) is a practical book with plenty of detailed photos and drawings.
Now In Bloom
Corydalis flexuosa brings vivid sky blue to the spring garden. This Royal Horticultural Society Award of Merit winner grows only a foot high, with masses of tube-shaped, white-throated flowers balanced in clusters atop the lacy foliage. It prefers moist soil and partial shade. Cultivars in varying shades of blue are available in the nurseries: 'Blue Panda' is gentian-blue and long flowering; 'Pere David' has turquoise blue flowers.
Valerie Easton is manager at the Miller Horticultural Library. Her new book, "Plant Life: Growing a Garden in the Pacific Northwest" (Sasquatch Books, 2002) is an updated selection of her magazine columns. Valerie's e-mail address is vjeaston@aol.com
