In nature every plant eventually is pruned in some manner. It may be a simple matter of low branches on forest trees being shaded by higher ones until they wither and die and are removed in a sudden storm. Or it could be that tender new branches of small plants are accidentally knocked off by wild animals looking for food. In the long run, a plant growing naturally will take the shape that is best for its location and climate.
In a garden you can help things along by pruning. Your reason may be to get a better shape or size or more and bigger flowers and fruit. Whatever your intent, pruning should usually be done in such a way that the plant looks as if it were growing naturally. Espaliers, hedges, and topiary plants are some of the exceptions.
PINCHING PRODUCES NEW BUDS
Each branch tip of a plant produces a growth hormone called auxin. This hormone causes the tip bud to produce new tissue, drawing nourishment and water from the plant through the cambium layer just under the bark. If the tip is removed, dormant buds all along the branch may begin to produce auxin.
When you pinch off branch tips, you signal the plant to produce new branches.Pinching doesn’t change the direction of plant growth — it just increases the number of stems and buds. To change the direction of a branch, you must find a fat bud growing in the direction you want the branch to grow. You then snip off the whole branch just above that bud. The bud will take over. For the same reason, you never pinch a branch that’s vigorously growing faster than the rest of the plant (pinching only gives you several vigorous branches). Instead, you cut off the branch at the base, or at least to a bud located well below the rest of the foliage.
LEARN THE DIFFERENCES IN PLANT GROWTH
Before any major surgery, study a plant’s growth habits. Each plant grows differently, and the right pruning techniques for one plant may mean death or disfigurement for another. For example, privet will often sprout lush growth if you cut it back to bare twigs. Do the same pruning to a marguerite and you’ll lose it. And, you’11 find that the pruning of some plants will produce little new growth. A good example of this is the camellia— pinch it back and you may get only one replacement branch. To produce several branches, you must cut back to the point where last year’s growth stopped and this year’s began [look for a difference in bark color).
Click graphic to see enlarged
examples of pruning techniques.
WHEN YOU’RE READY TO PRUNE
Some kind of pruning is necessary for most plants just before or at the beginning of the growing season. Major pruning on deciduous plants like fruit and roses is usually done in late winter when branches are bare. But you can also clean up, pinch back, or shear many plants in summer and fall—in fact, you have to if you want to keep a plant a certain size or shape.
The number one rule in pruning is: Never make a cut at an arbitrary point along a branch. Instead, cut just above a bud or a good branch, or make the cut flush with the trunk or base, trying to make the wound fairly small so bark will cover it quickly. If you cut between two buds leaving a stub, no nourishment will pass through the tissue below the cut. The stub above the bud will wither and die, offering a breeding ground for disease organisms that can damage the whole branch.
Shrubs and trees that produce flowers can be pruned after the flowers fade and just as new leaf growth is beginning. Since the plant is in an active growth stage, it will quickly heal the cuts you make. If you grow a plant specifically for cut flowers (roses perhaps) cut off every bloom with a view to shaping the plant; also, be sure to remove stubs and inferior branches.
Click graphic to see enlarged
examples of pruning techniques.
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Tim Lundie, Editor
