Many of us grew up with a Dad, or a Mom, who insisted on beating back the bushes with a hedge trimmer the moment they dared display the slightest sign of new growth. Never mind the mature height and unique form and habit of a given species, generations of homeowners were conditioned to believe that all landscape plants should somehow conform to one of a select few geometric forms: Globes, cubes, cones, and maybe even the occasional mushroom shape. But ask yourself, when would this ever happen to a plant in nature? The answer, of course, is never.
Educated gardeners understand that shearing plants causes stress, which leads to greater susceptibility to insects and other disease vectors. In fact, unless you are trying to enforce a particular landscape style, (Italianate, topiary, walled, parterre, etc) shearing is generally unwarranted. Since most shearing is performed as an attempt to control growth, the over-branching that results actually exacerbates the problem. Proper landscape planning takes into account the mature size of the plants, so they don’t need to be sheared out of the way when they encroach on the sidewalk or driveway.
Finally, shearing almost always destroys the plant’s crowning glory….its flower show! Whether the species in question flowers on last year’s wood or this year’s new growth, shearing will adversely affect the annual display. Next time you feel the urge to shear your plants because you assume it’s the right thing to do, consider enjoying that time on the couch instead, and letting the family enjoy the fruits, and flowers, of your horticulturally correct inactivity.