When to Prune Japanese Maples: For a Glorious Display
Knowing when to prune Japanese maples is an important aspect of caring for these garden stunners.
Japanese maples – also known as Acer palmatum – are some of the most beautiful trees you can grow. With their leaves turning a spectacular spectrum of dark purple to golden yellow and bright red in the fall, they are also the best trees for fall color.
While tall Japanese maples make delicious trees for shadethe smallest specimens are among the best trees to grow in containers.
However, to get the most out of these glorious trees, you need to prune them efficiently – and at the right time if you want them to put on their best show.
“It’s important not to over-prune Japanese maples, so take time throughout the year to observe your tree and get to know it,” says Pete Smith, arborist and urban forestry program manager. at the house of Arbor Day Foundation.
‘Do not prune your Japanese maple like other shade trees in your landscape. Instead, think of your specimen as a living sculpture that you create in your garden. It should be pleasing to the eye all year round, and that starts with proper pruning, judiciously applied each year.
When to Prune Japanese Maples – Expert Guide
Deciding when to prune Japanese maples is a common dilemma for gardeners.
“The best time to prune Japanese maples is in late winter, before bud break,” Smith says. “At this time of year, it’s easier to see the architecture of the tree; the way the branches are aligned and complement each other.
However, if you missed that window, it’s not too late as they can be pruned at other times of the year as well.
“Japanese maples can be pruned just about any time,” says horticulturist, arborist and expert Stuart Mackenzie at Trees.com.
“I like to prune my Japanese maples from late summer to early fall. I can top clean any unwanted growth; weak attachments are easier to spot. The awning can also be opened for better air circulation.
“By this time of year, the tree will have recovered from any winter damage and the disease will be easily identifiable. There will also be less bleeding (sap flow) now compared to spring.
When should you avoid pruning Japanese maples?
While in theory you can prune Japanese maples any time of the year, you should ideally avoid late spring and the height of summer.
If you prune too late in the spring, you will remove a lot of new buds, which could limit the tree’s growth potential for the year. “Ideally, wait until new growth has started, but before the leaves have fully unfurled,” says Lindsey Hyland, founder of Urban biological yield.
“This ensures that the tree won’t lose too much of its energy reserves when it starts to grow again.”
However, if the tree is out of shape and really needs pruning, you should go ahead and sacrifice new growth.
Severe pruning in the high summer heat can be problematic because it will minimize the shade benefits of the tree and also open the tree up to the scorching heat.
“Summers are typically stressful for Japanese maples due to high temperatures and long dry spells,” says Lindsay Pangborn, gardening expert at Bloomscape.
“Removing branches in the summer also exposes leaves and bark that were previously shielded from direct sunlight and can cause scorching and leaf drop.
“If you must prune in the summer, remove no more than a quarter of the foliage and wait for a period of cooler temperatures and regular rains.”
Can you prune a Japanese maple in summer?
Although heavy pruning should be avoided in high temperatures, light pruning to keep the tree in shape can be beneficial during the summer.
This is useful for “touching up” after further pruning in the spring.
However, avoid deleting too many branches at this time. “It can cause living tissue to break down and lead to disease or pests. You don’t want to compromise the tree,” Mackenzie says.
Does the formation of Japanese maples influence when to prune them?
Japanese maples are among the most ornamental trees, and many gardeners train them to keep them at a certain height or to grow in a certain shape, especially when practicing bonsai. Japanese maples are one of the most recommended bonsai types.
“When to prune Japanese maples depends on how you train them,” Mackenzie says. “Training for a desired shape effect will determine when to prune and how to prune. Trimming can also help release hormones that regulate growth and can actually slow growth.
You may also find that pruning Japanese maples is much easier if you train them into the shape you want first.
“You can do this by selectively removing branches as they grow, so the tree grows in the direction you want it to grow,” Hyland explains. “This will help keep your Japanese maple looking good for years to come and will make the pruning process much easier.”
How often to prune Japanese maples
“For regular landscape needs, once or twice a year is a typical frequency for pruning Japanese maples. If you keep pruning, you shouldn’t need to remove a lot each year,” says Pangborn.
“It’s fine to prune once every few years instead, as it gives new branches more time to grow and can help the gardener decide which branches to remove.”
If you perform a hard pruning on your tree – which is best in late winter – it is best to wait until the following year before pruning again, to give the tree time to recover.
“For specialty uses, like bonsai, it’s normal to prune much more frequently,” adds Pangborn.
Expert advice for pruning Japanese maples
- “Japanese maples are known for their picturesque shape. When trimming, step back frequently to get an overview and make sure you’re happy with the overall shape you’re creating,” says Pangborn.
- “When it’s time to prune, start by focusing on the branches that conflict with the aisles or those that compete with the center leader,” Smith says.
- “Trim off any dead or diseased branches first — along with the ‘suckers’ (sprouts that grow from the base of the tree) — then shape the tree as desired,” says Hyland. “By doing this, you are encouraging healthy new growth and strong structure for your tree.”
- “When pruning main branches, always use the three-cut rule to avoid unnecessary damage,” says Pangborn. ‘First, cut the branch close to where the final cut will be. Second, working on the outside of your undercut, cut through the branch to remove most of the weight. You will end up with a stub, which should be removed in the third step. Take care not to cut the collar of the branch.’
- “Never cut the branch collar, because the response cells are there,” adds Mackenzie. “If you cut too close or in the collar of the branch, the recovery is slow or not at all. This can lead to heartwood rot and disease.
- “Avoid pruning more than a third of the tree at a time,” says Hyland.
- “Pruning should always be done with sharp, appropriately sized tools,” says Pangborn. “Pruners are fine for branches smaller than the diameter of your finger, but for larger branches it’s best to use a pruning saw.”