Knowing how and when to prune Japanese maple trees is an important aspect of caring for these garden stunners. Pete Smith, arborist and urban forestry program manager at Arbor Day Foundation said: “It’s important not to over-prune Japanese maples, so take time throughout the year to observe your tree and get to know it. Don’t prune your Japanese maple like other shade trees in your landscape. Rather, think of your specimen as a living sculpture you are creating in your garden. It should be pleasing to the eye throughout the year, and that begins with proper pruning, judiciously applied each year.”
To prune Japanese maples, Bloomscape’s gardening expert Lindsay Pangborn advised: “When pruning, step back frequently to look at the ‘big picture’ and be sure you’re happy with the overall shape you’re creating.
“When pruning main branches, always use the three-cut rule to avoid unnecessary damage.
“First, undercut the branch close to where the final cut will be. Second, working on the outside of your undercut, cut through the branch to remove the bulk of the weight.
“You’ll be left with a stub, which should be removed in the third step. Take care not to cut into the branch collar.”
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However, if gardeners have missed this window, it is not too late as they can be pruned at other times of year too.
Stuart Mackenzie, horticulturist, arborist and expert at Trees.com said: “Japanese maples can be pruned just about anytime.
“I like to prune my Japanese maples at the end of summer to early autumn.
“I can crown clean out any undesirable growth; weak attachments are easier to spot. The canopy can also be opened up for better air circulation.
“At this time of year the tree will have recovered from any winter damage, and disease will be easily identifiable.
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“There will also be less bleeding (sap running) now versus the springtime.”
While in theory gardeners can prune Japanese maple trees at any time of year, they should ideally avoid late spring and the height of summer.
Pruning too late in the spring will remove a lot of new buds, which could limit the tree’s growth potential for the year.
Lindsey Hyland, founder of Urban Organic Yield said: “Ideally wait until after the new growth has started, but before the leaves have fully unfurled.
“This ensures that the tree won’t lose too much of its energy reserves as it starts to grow again.”
However, if the tree is out of shape and really needs pruning, gardeners should go ahead and sacrifice some new growth.
Heavy pruning in the high summer heat can be problematic as it will minimise the tree’s shade benefits, and will also open up the tree to scorching heat.
Lindsay explained: “Summers are typically stressful for Japanese maples thanks to hot temperatures and long periods of drought.
“Removing branches in summer also exposes leaves and bark that were previously shaded from the harsh rays of the sun and can cause scorch and leaf drop.”
If gardeners must prune in summer, the expert urged them to remove “no more than one-quarter” of the foliage and wait for a period of cooler temperatures and regular rainfall.
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