If Mother Nature had intended shrubs to be square, she would have created them that way. Yet humans persist in trying to render a free-growing plant into geometric perfection.
It's certainly not a new phase. Europeans have been shearing for centuries. Maybe it's the result of an innate desire to dominate nature. Or it could be a symptom of obsessive-compulsive disorder manifested in gardens. But the biggest problem of all is that shearing shrubs into boxes, rectangles, balls and pyramids turns easy-care plants into a lot of unnecessary work.
As a student and residential gardener, I hated homes with sheared shrubs or those "poodled" into strange Dr. Seuss shapes. They required me to frequently shear the plants, and then rake up the clippings and dispose of them. This added a great deal of time to an otherwise low-maintenance landscape job.
Shearing plants often begins as an effort to make a big plant fit into a small space. If selected properly, there should be no need to prune most shrubs at all. A good designer will assess the space provided and then select a shrub that will fit perfectly. Planting anything without prior knowledge of its mature height and diameter inevitably leads to a lifetime of shearing.
My mentor was a stickler for what he called natural pruning. "The shrub should never look as though it's been pruned," he would say. "And if done properly, you rarely have to prune at all." In his mind, natural pruning wasn't just a visual choice; it was a method to keep shrubs healthy. He knew from 50 years in the field just how much work results when shrubs are sheared rather than pruned.
When you shear a shrub, you are cutting only the outermost twigs and leaves. This makes the shrub grow back faster as it tries to protect its newly exposed limbs. A shrub pruned this way is usually hollow on the inside surrounded by a dense outer layer of foliage.
Natural pruning accesses the interior framework of the shrub to remove unwanted growth from its source. This process not only helps you better understand the growth habit of the shrub, it disguises the cuts behind the outer leafy cover. To reduce the overall size, prune out whole branches that support the unwanted foliage. This method is excellent for encouraging new limbs to be produced from the base of the plant or low on the trunk. These new limbs are vigorous, producing more flowers and larger fruits.
There is one guideline that applies to both sheared and naturally pruned shrubs. Always shape a shrub so it is progressively wider at the base than at the top. Even if it's just a slight differentiation, the effect ensures that the upper limbs never shade the bottom ones. Shading causes leaves to drop, resulting in "bare legs." This allows sunlight to reach the soil under the shrub, stimulating weed growth and causing yet another maintenance task. So whether it's a lilac or a camellia, keep things slightly narrower at the top.
Sheared shrubs do not fit into "green" landscaping. It robs shrubs of their best qualities and generates a tremendous amount of unnecessary green waste. It also demands time and labor on a frequent basis. And saddest of all, the natural beauty of that species conceived by Mother Nature in all her wisdom is forever lost to the ravages of electric hedge clippers and leaf blowers.