This Is the Worst Time to Trim Your Hedges, According to Gardening Experts

A hedge is a dense planting of shrubs or small trees that form a natural fence around an area, offering a beautiful way to add privacy, height, and texture to the landscape. Without proper care, hedges can become unruly and lose their shape, taking away from their intended purpose of creating a defined border. Trimming is essential to ensure your hedges look their best and maintain their shape year-round. But that doesn’t mean you should take shears to your hedges any time they look disorderly. Trimming hedges at the wrong time can do more harm than good. Ahead, experts share the best and worst times to trim hedges to ensure yours stays healthy and defined. 

When to Trim Hedges

When you trim your hedges depends greatly on the type of shrubs or trees in your hedge. "Not all hedges are treated the same, as it will depend on the genus and species of the plant," says ISA Certified Arborist Eva Monheim. "There is no one-size-fits-all, especially when dealing with large-leaved hedges." Research the specific plants in your hedge to know when you should cut them back.

That said, many hedges consist of evergreen plants, which Monheim says can be trimmed before or after growth emerges. "[They] can be trimmed in late winter before the flush of new growth emerges so that they have a soft appearance when the new growth hardens off," she says. "Or they can be trimmed after the new growth has hardened off in or about June for a sharp, austere appearance."

The Worst Time to Trim Hedges

While the right time to cut your hedges varies, there is a time when you should never trim your hedges. "The worst time to trim hedges is when they are actively extending their new growth," says Monheim. "It takes a great deal of energy to put out new growth on any plant. It’s the first time the plants are photosynthesizing after the long winter for deciduous plants." She adds that it's critical to wait until the new growth hardens off before pruning trees or hedges. "This is when the plant is stable and won’t wilt after pruning. Young, new growth is photosynthesizing and building new parts of the plant," she explains.

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Consequences of Trimming Too Late

Pruning too late in the season is a common mistake people make when trimming hedges, according to landscape designer Teri Speight. "Pruning too late can cut off the next season's blooms or encourage new growth at the wrong time," Speight says. "This can also lead to frost or freeze damage." She explains that encouraging new growth after a late-season prune could be detrimental to the tender young growth that won't have time to harden off before colder temperatures set in. 

Consequences of Trimming Too Soon

Trimming hedges too early in the season can cause its own set of issues. "If you trim shrubs too early in the season, you can encourage a growth spurt that would be prone to frost or even freeze damage," says Speight. Wait until after the threat of frost has passed to cut your hedges.  

Hedge-Trimming Tips

Try these expert-recommended tips to help make your hedge-trimming job easier and more successful.

Use the Right Tools

Different tools are needed for different types of cuts, so research the right tools to use before trimming your hedges. "Large-leaved shrubs are not typically pruned with shears but rather with hand pruners," says Monheim. "This pruning is for the more skilled person who will take the time to prune each stem back to the nodes so the cuts are not visible to the viewers and will help to regenerate healing quickly." Examples of this include leatherleaf viburnum (Viburnum rhytidophyllum ), panicle hydrangeas (Hydrangea paniculata), and smooth hydrangeas (Hydrangea arborescens).

On the other hand, some conifers are bud-pruned (pinched) to redirect the new growth or reduce new growth, never sheared with hedge shears. "A good example of this would be spruce hedges," she says. "These can also be hand pruned with pruning shears back to a node."

Let Light In

Speight recommends leaving the base of foundation shrubs a little wider than the top to avoid poorly shaped hedges. "Allowing light to get to the inside of most hedges will encourage new growth from within and not spindly, erratic growth, which can happen with improper pruning," Speight says. She suggests keeping a journal that can remind you of what plant material you're growing, when pruning should occur, and how to prune it. 

Use Sharp, Clean Tools

Sharp, clean tools are vital for optimal plant health. If your tools are not sharp, they will tear the leaves and stems, resulting in browning on the surface of the shrubs after pruning, says Monheim. Both experts recommend cleaning and sterilizing your tools before and after pruning to prevent carrying diseases from one group of plants to another.