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Pruning Trees and Shrubs in Late Winter

Got pruning tools ready? Perhaps you should. Late winter is a great pruning season; overgrown branches and dead wood can be safely lopped away. Pruning helps to produce healthy, attractive trees and shrubs with maximum flowers. Unfortunately, there is no “one size fits all” approach to the activity. It may be one of the least understood landscape practices.

“The advantage of pruning in winter is that we can see all of the tree’s structure,” says Jeffrey Ward, Ph.D., chief scientist in the Department of Forestry & Horticulture at the Connecticut Agricultural Experiment Station (CAES). “It also easier to spot and correct defects such as crossed branches and branches with cracks.”

Ward says that after a winter cut, the tree begins to grow callus tissue as soon as growth resumes.

“New growth begins in late winter,” he says. “As sap begins to flow, there’s hidden formation of new bark cambium and new vascular tissue—phloem and xylem.” Some trees, such as maples and birches, will exude sap after a winter cut. “It may be unsightly but is not harmful to the tree,” says Ward.

A winter-pruned tree has a chance to heal before pathogens become active in spring and summer. This is an especially good time to prune non-flowering deciduous shrubs and shade trees such as maple, oak, and elm, as well as summer-flowering species such as Rose-of-Sharon, viburnums, and summersweet. It is also a fine time to prune needled evergreens.

“You can prune almost everything in winter,” says Ward.

Almost? This word causes some to hesitate before the handsaw.

Here are some broad exceptions: Skip over the spring-flowering species, such as azalea, rhododendron, magnolia, forsythia, chokeberry, and lilac. Prune these after they have finished flowering.

If you never got around to pruning your bigleaf or oakleaf hydrangeas last year, don’t do it now. Hydrangea macrophylla, Hydrangea serrata, and Hydrangea quercifolia all form flowers on last year’s wood. You’ll be taking off 2016’s blossoms.

CAES’ Jeffrey Ward adds, “From personal experience, I would not recommend pruning hollies, butterfly bushes, or roses until the new buds begin to open. If you prune them earlier, the branches will die back a few inches from the cut.”

CAES publishes a comprehensive introduction to pruning at bit.ly/Pruning-WhyHowWhen.

At the UConn Home and Garden Center, extension horticulturist Carol Quish reminds us to avoid cutting the “collar” tissue that forms the junction between trunk and branch. Always cut about 1 inch to 2 inches above the collar; never make a cut that is flush with the trunk. Use a hand saw where possible, not a chain saw.

Quish also mentions that if a branch appears to have a disease or insect, clean the cutting tools before moving on to another plant. She suggests a solution of either 10 percent alcohol or bleach in 90 percent water. You can call the Home and Garden office at 877-486-6271 for more information.

Ready for a hands-on introduction? Connecticut College Arboretum will offer a session on The Art and Science of Pruning on Saturday, March 26, from 10 a.m. to noon. See www.conncoll.edu/the-arboretum/programs-and-activities.

As for Internet resources, there are many. I like Cass Turnbull’s humorous spin on her “Plant Amnesty” site, www.plantamnesty.org. Turnbull is also the author of Cass Turnbull’s Guide to Pruning (Sasquatch Books, 2012), available at the Madison and Branford libraries.

Lewis Hill is one of the most prolific authors on do-it-yourself pruning. His Pruning Answer Book (Storey Publishers, 2011) is at the libraries in Essex, Durham, and Ledyard. His Pruning Made Easy (Storey Publishers, 1997) is located at East Lyme, Guilford, Hamden, Ledyard, and Old Lyme.

One final thought: If you decide to hire help, be aware that only a licensed arborist can offer pruning services in Connecticut.

Kathy Connolly is a landscape designer, garden writer, and speaker from Old Saybrook. See www.SpeakingofLandscapes.com.