At a gardening presentation on pruning, a woman in the audience quietly but firmly asked how anyone could possibly cut parts off plants. “It’s cruel and unnatural,” she said, adding that she just couldn’t bring herself to cut a branch off one of her trees.
In some ways, all gardening is unnatural, including watering, fertilizing, mulching, weeding – any intervention that goes beyond what nature would do. But pruning scares even otherwise bold, talented, creative gardeners. Many say they don’t like to prune or don’t know how to prune, or they fear making mistakes that never can be corrected. Every gardener makes mistakes, but most learn from them.
Pruning starts with the purchase
Look for plants with the potential to look artistic and interesting. Sometimes it means buying trees and shrubs that others have shunned as twisted and gnarled. And it means looking at such plants and visualizing what they’ll look like with pruning. Call it a search for the inner tree.
In some ways, this is using the same criteria applied when choosing trees and shrubs for bonsai subjects. You can think of many plants as bonsai in the ground.
Speaking of bonsai, there is an instructive tale centering on pruning. A student asked a bonsai master when it would be the best time of year to prune. The student expected the answer to depend on whether the tree was deciduous or evergreen, or whether it was about to bloom or had just bloomed. He was surprised at the master’s answer: “When should you prune? Whenever the knife is sharp.”
Yes, if you are pruning shrubs like lilac or rhododendron or magnolia, you might want to prune just after they bloom, but there’s no magic about waiting until cold weather has passed. Just as experts now acknowledge there’s no magic about protecting pruning cuts with paint.
The 3 main reasons to wield the knife
1. Health. Some shrub branches, particularly pieris, die back for no apparent reason, then get attacked by fungi, which could spread, causing wood to decay. It’s important to prune these stubs immediately, as well as those resulting when a falling limb crashes down, breaking a branch. Equally important for avoiding disease is taking care not to leave stubs when pruning. Also, shrubs and trees are made more attractive when their forms are opened up from pruning interior branches. Pruning admits beneficial air and light.
2. Size. Some gardeners who have planted densely want to keep gardens at a certain scale and plants at certain heights and widths. An efficient way to do that is to cut off the leader in a tree, such as an upright Japanese maple, keeping it in scale and promoting more growth in side branches. With hydrangeas, you can make it easy on yourself by disregarding whether blooms form on old or new wood, pruning only when the plant has grown larger than you want. Most people following this practice say they always get enough blooms. Eventually, after years of pruning and shortening, some trees start to stand out in a bad way, leaving only one solution for a too-short, fat-trunked tree: removal, the ultimate prune.
3. Art. This is, of course, in the eye of the beholder, and when many pruning people behold, they want to see movement in their trees and shrubs. Motion as art. Yes, straight trunks on some trees, spruce, and bald cypress, for example, can be beautiful. But others may look especially artistic when they swoop, soar, and dive. Some plants have natural rhythm, notably mountain laurel, threadleaf Japanese maple, pieris, lilac, sumac. But even their rhythm has to be uncovered; weeping maples benefit from having lower growth pruned away from their trunks along with growth along the branches, leaving only the “clouds” at the ends. To complete the unveiling, prune away the skirts that drag the ground and conceal trunks of these trees. This gives the tree lift and better shows off its natural curves.
What if you cut too much?
Unlike a bad haircut, some prunings last forever. Such was the case with a fine paperbark maple. To keep the tree away from the house (it had been planted too close), a Connecticut gardener cut off several branches, but the tree looked pitiful, scalped. So he cut the canopy down to a couple of feet above the trunk, leaving just a half-dozen branches. These headed branches put out vigorous growth each year, and in every late winter the man cut back all that new growth. Eventually, club-like stubs formed at those branch ends. The look was striking. The gardener had created his first pollarded tree; the maple was saved. And it fit the space. He liked the result so much, he found additional pollarding candidates he could intentionally redo.
If you find yourself aghast at the radical pruning of your Japanese maple, for example, give it time, and you will come to appreciate your tree’s new look.
Lee May, author, journalist, and gardening writer, lives in East Haddam, Connecticut. Read his blog at LeeMaysGardeningLife.com.
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