Last week I was visiting with a customer. We were walking his property and discussing the various maintenance needs of his plants. While a few plants needed selective pruning to remove dead, diseased, damaged or unsightly shoots, many plants needed shearing.
Several herbaceous perennials needed last year’s dead growth to be sheared off completely, being careful not to damage this year’s new shoots already aggressively growing. (If this type of shearing is done after late fall’s freezes and before spring’s new growth, often the shearing can be right to the ground). But beside these herbaceous specimens, there were also shrubs that needed shearing.
He had contacted me in order for me to shape the boxwoods that ornament each side of his front porch. This is the type of shearing that most people think of when they say “cut the hedges.” In this type of shearing, non-selective cuts are made in order to shape the plant. In the photo, I am shown working carefully to ensure that both boxwoods match as exactly as possible in shape and size.
For this type of shearing, it is necessary not only to go slow but to cut the same areas repeatedly. For this reason, angular hedges are much easier to cut well; all shoots must be removed back to the desired plane.
In spherical or conical shapes, however, it is necessary to use a flat blade to produce a curved appearance, and this requires more time. Because of the amount of effort required, and because a display of a menagerie of shapes looks goofy, I recommend only maintaining a few of these geometric exhibits.
In contrast to this type of shrub shearing, however, there is yet another type of shearing I discussed with the customer. Behind me in the photo there is a “hedge” of spirea. From its form, it appears it escaped any pruning last summer. But as I pointed out to the customer, while its size – and to a degree its form and growth habits – do not demand shearing, its bloom potential does.
Within two months, this hedge will be covered with short-lived flowers. This is why I recommended not touching it now. We don’t want to risk damaging or delaying that bloom. After that bloom is finished, however, the plants can be promptly sheared. This shearing will result in new growth and a second bloom late in the growing season.
For this type of shearing, while the general shape still matters, it is a speedy buzz cut. This light, quick cutting does not shock the plant, but reduces the size a bit and encourages response growth, prompting a new bloom.
With spirea, regular shearing not only keeps the plant blooming, but also prevents it from getting leggy. But with regular shearing, the plants will also eventually need to be thinned.
Joshua Arp is an ISA-certified municipal specialist, Clarks Summit’s municipal arborist and an operator of an organic lawn and landscape maintenance business. Reach him at firstname.lastname@example.org.