Pete Duncombe will cover the basics of pruning shrubs at 8:30 a.m. today, Saturday and Jan. 29 at the Springs Preserve, 333 S. Valley View Blvd. In his fun way, he’ll show you the following principles as he does his nipping.
The advent of the new year signals the beginning of spring gardening. Many plants are ready to wake up. The remnants of last year’s fallen leaves are nestled on the ground like a blanket.
With spring just around the corner, we’re entering full cleanup mode with a flourish of activity to prepare plants for the next season. While pruning can occur at any time of the year, now is the time for heavy pruning of shrubs. Exceptions to this are spring’s flowering shrubs that bloom on last year’s growth; heavy pruning greatly reduces their effect. For almost everything else, pruning now directs growth; rejuvenate in anticipation of spring growth eagerly waiting to erupt.
Over the years, gardeners have developed philosophies and approaches to pruning that provide the greatest results. The overarching philosophy embraces the natural landscape and advocates the approach of maintaining plants in a naturalistic fashion. We achieve this in the landscape through selective thinning to open up growth and let in light and preserve the natural form, rather than shearing, which generally has the opposite effect.
Unfortunately, shearing has gained more popularity and become the norm. We can see examples of this everywhere in streetscapes that are heavily maintained. Gangs of gardeners assault landscapes with power hedgers and blowers, relentlessly beating plants into submission to keep them in bounds.
Constant shearing causes dense growth to form at the circumference while the interior of the plant dies. Ultimately, this approach makes the health and growth of landscapes unsustainable.
Pruning really starts with choosing plants that fit the space rather than continually pruning them back to make them fit. If you severely shear two or three times a year, then it’s the wrong plant for the space and you should replace the plant. While shearing with power hedgers seems easier, in reality it’s more work and must be done more often to maintain the manicured appearance. It is more difficult to learn the skills for naturalistic pruning, but in the end it’s much less work and better for the plants.
There are four basic approaches for proper health and growth of plants: naturalistic, selective thinning, rejuvenation and leave it alone.
Naturalistic pruning is the best approach to managing native and desert-adapted species to maintain the natural form. You accomplish this by dead-heading flowers and making thinning cuts to open the canopy and encourage new growth from within.
Selective thinning differs only in that it requires a more managed approach, but the result is the same — to maintain the natural shape of plants.
The goal of rejuvenation is to reinvigorate plants by systematically removing older growth and encouraging new growth from the base. The general approach is to prune shrubs down by a third and remove a third of the branches down to the ground every year. The result is a complete rejuvenation of the shrub every three years. In more severe cases, you can “radical” rejuvenate by pruning to the ground and allowing new growth to come up from the base. This is a good approach to treating shrubs that have been sheared for years and are now failing.
The last method is the leave-it-alone approach. This works well in a landscape where plants just grow naturally. It is great for wildlife habitat development and lower-intensity landscapes.
We prune shrubs to keep them in vigorous condition. Remove branches that are dead, broken or extending beyond the face of curbs or sidewalks.
Formal hedges and topiary need regular pruning, but it’s best to let shrubs grow naturally. Hedging causes dense, continuous growth and branching fully to the ground. Prune all other shrubs as required for safety, visibility and for good plant health.
Prune plants that are sensitive to freezing after the last frost. In the event of a deep freeze, allow shrubs time to rejuvenate before removing the damaged wood.
Duncombe wants you to remember never to make cuts without good reasons and an understanding of how shrubs grow. Get the know-how by attending one of Duncombe’s pruning workshops.
Linn Mills’ garden column appears on Sundays. He can be reached at linn.mills@ springspreserve.org or 822-7754.