HALT!!! Put the pruning shears down, and step away from the shrub!
Now, ask yourself this simple question: Why am I pruning this plant? If you answered, "Because it's Spring, and now is the time to prune," or you answered, "Because my wife told me to," then I would encourage you to stop your seasonal shearing and take some time to consider your intentions with those pruning shears.
The purpose of my challenge is not to force you to justify your actions, but rather to illustrate that the answer to this question can help you to understand the so-called Do's and Don'ts of pruning and to help ensure that you get the results you want.
CONSIDER THE REASONS FOR PRUNING
Because this plant is too big:
If your answer to my question is "Because this plant is too big," then you need to proceed cautiously. A good rule of thumb is never to prune more than 1/3 of a plant. Then observe how the plant responds to pruning. If next year more foliage needs to come off, keep pruning till your shrub fits the space you have. Some plants with a vigorous habit, such as Pacific Nine Bark, Smoke Bush, and Elderberry, can handle severe pruning and can be manipulated into fitting into a smaller garden space. In fact, some plants do well when pruned back hard each spring.
If you have experience with a particular shrub and have confidence that it responds well to heavy pruning, then grab your shears and proceed as usual. If, however, you are not sure what kind of shrub you are pruning your best option is to go slow. Your patience will be repaid with a well-shaped, healthy shrub.
Of course, trees should NEVER be topped. Tree topping creates ugly hazards out of trees. And, ultimately, the practice does not succeed in keeping a tree small. The previous owner of my home regularly topped his trees. And last year I had to remove two 30-foot tall fir trees (that should have been 60 feet tall) that had begun to die.
For a great explanation of why you should never top your trees, I suggest you refer to Plant Amnesty, an organization dedicated to preserving the health of trees in our community.
Because I want to promote lots of new growth:
If you have decided to prune your shrubs because you are trying to promote healthy growth, then your timing is right. But you still need to be selective about the shrubs you prune. If the shrub you plan to cut back is a flowering shrub, such as an azalea, rhododendron, or hydrangea, you need to decide if you are willing to sacrifice a season of blooms.
Pruning a spring flowering shrub at this time will likely cut off all of this season's flower buds. If you want to see your rhododendrons bloom this spring, it is best to wait until after they are finished blooming. If you are okay with losing a season of flowers on your shrub, the best time to prune is late winter or early spring. While pruning the ornamental shrubs at this time will reduce or eliminate blossoming this spring, you will gain healthier, more vigorous ornamental shrubs in the long run. If you have ornamental shrubs that bloom in summer or fall on the current year's growth, prune in the winter.
Because this plant just looks wrong:
If you are looking at the plants in your garden and thinking to yourself, "My bushes look odd," pruning may very well help. Bushes with a dense, compact habit, such as Privet or Boxwood, can be pruned to any shape, even that of a poodle. But if you want a more open, natural-looking shrub, then a couple of rules should be applied when pruning your bush.
First, thin out the shrub by cutting unwanted branches to a ¼ inch from the main branch. Leaving too much branch sticking out makes unsightly stubs.
Second, trim back branches to an outfacing bud. At this time of year buds are easier to spot because they begin to plump up. Some gardeners describe them as teeny-weeny eyes on the branch. By cutting back to a healthy bud that faces the exterior of a shrub, you will promote new growth out away from the center of the plant, opening up the plant's foliage and giving the plant a more natural look, and better air circulation for preventing fungal and bacterial disease.
IT'S HARD TO GO TOO WRONG WITH SPRING PRUNING
Many gardeners look forward to pruning their shrub with a bit of fear, mystified by all the information floating around in books, magazines, and the internet. If you are feeling a little daunted and discouraged about shearing your shrubs, take heart. Plants are tough, living creatures that can endure significant abuse.
The best rule of pruning that I have come across is to be patient. Be patient while pruning, and you are less likely to cut a branch that should not be cut. Be patient while waiting for your tree or shrub to look the way you really want it. If you missed a branch one year, you can cut it the following year, and your shrub will look great for years to come. And if you have any doubts, contact your favorite nursery for guidance.
Photo credit: By ti_lapin_tom