Just because the growing season is coming to an end doesn’t mean that your work in the garden is through. Many plants, trees, and shrubs require pruning during different times of the year so that they can continue to thrive, even during dormancy.
Ahead, learn what our garden experts say about when you need to stop pruning your garden plants, including the best time of year to break out those shears and get cutting again.
Why You Should Stop Pruning
Knowing when to stop trimming your plants back for the season can be tricky, depending on what plant material is in question, according to Sara Abbass, owner of Sara Mairead Landscape Design and co-founder and executive board member of Northport Native Garden Initiative.
“Native plants may differ from non-native plant species with when the best time to prune may be, but an important consideration, no matter the plant in question, is when does this plant bloom,” she says.
If you prune too early or too late, you risk unintentionally cutting blooms that are already set or on the verge of budding out, causing your plants to lose an entire season of growth.
When to Stop Pruning Trees
The last time you should cut your trees back for the year depends largely on the types of trees you’re working with. For example, fruit trees are best pruned in winter, according to Bevan Shimizu, owner of Shimizu Landscape Design. “Deciduous trees are best pruned just as the new growth is emerging in late winter/early spring,” he continues, adding that evergreen trees are best pruned either in late winter/early spring or summer.
“Crepe myrtles you can prune in late winter. Many people prune them back very hard; this is called ‘Crepe Murder.’ I find it more attractive to selectively prune branches and give it a more natural appearance since the trunk is so beautiful.”
And then there are the trees that require a pro’s help. “For large canopy trees, it is best to consult an arborist, especially if it is leaning towards a structure or has overhanging or dead branches,” Shimizu says, adding that it’s good to cut crossing branches on trees or branches that are touching when you do trim those larger trees.
When to Stop Pruning Shrubs
If you’re wondering when to stop cutting back your shrubs, Shimizu says it depends on the variety as well. For example, he says you should prune your roses in the winter. “You can also deadhead flowers throughout the growing season to get more flowers.”
On the other hand, he says most spring-blooming plants need to be pruned immediately after flowering because they bloom on old wood. “This includes plants such as azaleas, lilacs, and Spiraea.”
Abbass notes that plenty of shrubs continue to bloom throughout the season, which means you’ll need to pay close attention to when they stop flowering for the year so that you know when the timing is right. “Many of these plants, such as ‘Arctic Fire’ red twig dogwood, will be setting their blooms late spring/early summer, following their early spring show of blooms,” she says. “An ideal time to prune this type of shrub would be immediately following their bloom period. Similar for shrubs such as Ninebark and Sweetspire.”
Summer flowering shrubs, such as caryopteris, clethra, and weigelia, are best pruned in late winter/early spring, Shimizu says. “With hydrangeas, it depends on what type of hydrangea it is. Smooth hydrangeas are pruned in late winter, big leaf hydrangeas in late summer, oak leaf hydrangeas in late summer after the flowers fade, and climbing hydrangeas in early spring and long shoots after flowering.”
“Shrubs such as witch-hazel are absolutely stunning in the winter months, but you certainly don’t want to lose those beautiful blooms,” Abbass says. “Make sure that if any pruning is necessary for shrubs—such as winterberry (Ilex) for example—that they are minimal and trimming is done immediately after bloom.” Otherwise, she says you may risk losing berries on plants like these if you trim too aggressively or too late in the fall.
When to Stop Pruning Perennial Plants
Shimizu says that he prefers to leave dead perennials in the landscape over winter. “They provide habitat for insects and create interest in the garden,” he explains. “As the designer of The High Line, Piet Oudolf, says, ‘Brown is a color too.’”
That being said, Shimizu does prune back dead perennials in February or March, before new growth emerges. “Some people like to cut back dead perennials in late fall to give their garden a more tidy appearance.”
When addressing fall cutbacks, Abbass agrees that you should consider leaving some plants, such as grasses, for both winter interest in your landscape and a place for hibernating pollinators. “Grasses can be cut in the spring and still reach full size in their peak season.”
When to Start Pruning Again
Shimizu says that there really is no hard and fast rule for pruning. “The answer, as it is with everything in life, is ‘it depends.’” But he does note that there are some things to make it simpler.
“Know whether your plant blooms on old wood or new wood,” he says. “That will affect how you prune it. If it blooms on old wood, don’t prune until after it flowers. If it blooms on new wood, cut it back in early spring.”
And make sure you’re not cutting too much off at any given time. “Generally don’t prune more than 25 percent of any tree/plant,” he adds, saying that you should always prune anything in a walkway or sidewalk, especially things at eye level.
