Does your Japanese Maple need pruning? These trees seem to effortlessly develop an elegant structure as they grow. As a result, many gardeners wonder if there’s any need to trim them at all. However, there’s a good case to be made that you should prune a Japanese Maple occasionally if you want the healthiest, best-looking tree possible. Read on to learn the best times, techniques, and tools for Japanese Maple pruning.
A young Japanese Maple needs very little pruning, though a few cuts in the right places can help steer it toward a pleasing shape. As the tree matures, you should occasionally thin out the canopy to increase light and airflow. Careful trimming can also help you control its size. It’s best to prune a Japanese Maple in the summer (for size) or the winter (for shape).
One important thing to remember as we proceed: less is often more when it comes to pruning Japanese Maples. These trees grow slowly, so if you’re not certain you should make a particular cut, it’s often okay to think it over for a year or two! The only exception is removing dead or diseased wood, which should happen as soon as possible. See below for our detailed instructions on the right way to trim a Japanese Maple.
Why Prune a Japanese Maple?
To hear some gardeners tell it, there’s basically no reason ever to trim your Japanese Maple. We think that’s a bit of an exaggeration. While it’s good to be conservative with your cuts, there are actually quite a few scenarios where pruning your tree is the right move.
The most common type of trimming is a simple cleanup cut to remove dead or dying growth. Extreme heat or cold can damage these trees, and it’s not uncommon to see a bit of dieback during both winter and summer. It’s best to remove this dead tissue before it rots and spreads decay to the healthy parts of the tree. And you should take off any branches showing signs of diseases like wilt, cankers, and leaf or twig blight.
Correct pruning can also improve the overall health of your Japanese Maple and encourage vigorous growth. If the tree’s canopy is too dense (particularly in the “weeping” varieties), not much light or breeze can get through. Lack of sunlight can stifle the foliage on the lower or shorter branches, limiting your maple’s energy intake. And densely packed branches with little airflow are more susceptible to disease.
Clipping back a Japanese Maple may also help you limit its size. You can combine this practice with some structural pruning to steer its growth away from nearby structures and walkways. It’s always best to choose a variety with a mature size that fits the space, but the right pruning techniques can help you keep your tree on the small side.
Finally, you can prune your Japanese Maple to help define its shape as it grows. Japan’s native Acer trees have a natural elegance, but savvy pruning can often enhance and emphasize their inherent beauty.
How Old Should A Japanese Maple Get Before You Prune It?
Here’s a quick guide to pruning your Japanese Maple at the various stages of its life cycle:
Don’t Prune Young Japanese Maples More Than You Have To
Some argue that any pruning except to remove unhealthy growth is inappropriate until your Japanese Maple is 10-15 years old. We respectfully disagree. If you’re careful, there’s no reason you can’t start sooner.
It is usually best to limit trimming when the tree is very young, though. When Japanese Maples are first growing in, they often produce a profusion of slim, whippy branches. You may be tempted to remove these, but often this only encourages even denser clusters of twigs to appear. Instead, allow the tree’s inborn instincts to guide it for at least the first 2-3 years of its life. In time, those thin little twigs will turn into thick, graceful limbs with side branches of their own.
One important exception: clip back any shoots that start to emerge from below the graft union. Almost all Japanese Maples are propagated by grafting a cutting of the desired variety onto generic Acer palmatum rootstock. Make sure you know where the two plants merge — it should be very close to the base of the tree. The trunk will have a slight scar at that point and may look slightly crooked, and the bark may look different above and below the junction.
Any growth coming from below this point will look like the older, less valuable tree, not the cultivar you paid for. Clip it off before it siphons energy away from the rest of your Japanese Maple.
Lightly Prune and Shape Juvenile Japanese Maples
After the tree develops for a few years, you should start to get a sense of the shape it’s taking. Now you have some decisions to make:
- Are you aiming for a specific look? You can start training and shaping your Japanese Maple now.
- Do you want it to grow large as quickly as possible? Trim away some of the smallest branches to free up energy for the main limbs, encouraging faster growth.
- Is your goal to limit the tree’s size? Leave the twiggy stuff in place and prune your Japanese Maple only for shaping purposes (and to remove deadwood).
Prune Mature Japanese Maples Regularly
Once your Japanese Maple is around 10-12 years old, it should be much closer to its mature size and shape. You’ll likely notice its growth slowing down somewhat. At this point, you may need to start pruning your Japanese Maple for maintenance roughly once per year. Though it’s not expanding as quickly, it will often produce dense foliage that calls for regular thinning.
What’s the Best Time to Prune a Japanese Maple?
The right time of year to clip your tree depends a bit on what you’re hoping to accomplish.
Autumn: Don’t Clip Your Japanese Maple
In general, you should avoid pruning in the fall. Fungal diseases are more prevalent in autumn due to the cold, damp weather and profusion of decaying vegetable matter. Cutting off branches increases the odds of infection by exposing the inner tissues of the tree.
If you see dead or decaying growth on your Japanese Maple, go ahead and clip it off regardless of the season. But don’t do any substantive trimming in the fall.
Winter: Prune Your Japanese Maple For Structure
The late winter or early spring is often a great time for structural pruning designed to beautify a Japanese Maple. You can easily see the layout of the limbs when they’re not obscured by leaves. If you’re planning on making changes to the tree’s overall shape, do it in February or March.
Spring: Trim To Invigorate Your Japanese Maple And Steer Its Growth
You can also wait to prune a Japanese Maple until it’s forming new leaf buds for the season. This allows you to see which way the newest growth is heading, allowing you to shape the tree with great precision. By trimming a small branch back to a specific set of buds, you can control which way it will sprout. Simply rub or clip one of the buds off to ensure that the new growth comes from the other one.
As long as you do your pruning before the buds break and leaf out, you shouldn’t hurt the tree. In fact, any remaining branches will often grow all the more vigorously since the tree has more resources for them. A Japanese Maple pruned at the start of the growing season will often respond with a bold flush of growth.
Once the leaves begin to emerge, it’s best not to prune your tree. The new growth is fragile at this stage. And although pruning wounds heal faster in the spring, they also ooze more sap. This can slightly increase the chances of fungal growth.
Summer: Thin And Reduce Your Japanese Maple
Summer is a good time for thinning out your Japanese Maple’s canopy. You can see the effect in real-time as you remove the smaller branches, increasing visibility into the interior foliage.
Late summer is particularly good for reduction pruning designed to keep your tree’s size in check. Cutting at this time removes some of the sugars your Japanese Maple is stockpiling to fuel next spring’s growth.
One important warning about summer pruning: stick to days when the temperature is below 80 degrees Fahrenheit. Japanese Maples prefer partial shade, and removing their foliage increases their sun exposure without giving them time to acclimate. It should only be done in relatively mild weather.
What You’ll Need to Prune a Japanese Maple
We’re going to give you a detailed guide to trimming, shaping, and thinning Japanese Maple trees. First, though, we need to talk about the tools and materials you’ll need. Here’s a basic list:
- Bypass pruners. These sharp, spring-loaded shears let you make clean cuts through smaller twigs and branches.
- Loppers. Long-handled loppers allow you to reach further into the interior of the tree and add extra leverage for cutting. Use them for pruning Japanese Maple branches that are roughly finger-width.
- Pruning saw. If you need to perform structural pruning, removing branches that are thicker than about 1.5 inches, use a hand saw. This will give you a smoother cut than trying to force your way through a big branch with clippers.
- Gloves. A little bit of extra protection may help you avoid cuts when handling sharp tools. It may also keep your hands from getting sticky with sap.
- Eyewear. Perhaps not strictly a necessity, but never a bad idea when you’re working with whippy branches.
- Disinfectant. Cleaning any germs off of your tools is a must when pruning, or the cuts you make could get infected. We suggest using rubbing alcohol or a mild bleach solution as a sanitizing agent.
- Shade cloth. Planning to trim a Japanese Maple during the summer and worried about sun scald? Setting up a bit of shade cloth over the newly exposed bark could help shield it from the worst effects.
How To Prune a Japanese Maple: An Overview
The following guidelines should help you trim your maple effectively in just about any scenario. We’ll get into more specific pruning techniques a bit further down, but you should always keep the following tips in mind when cutting your tree.
Prune Dead And Unhealthy Wood First
No matter why you’re pruning your Japanese Maple, it’s best to clear away the detritus first. Japanese Acer trees often experience some dieback from winter frosts, while disease and lack of sunlight can kill branches any time of year. And sometimes, a thirsty or stressed-out tree will simply stop feeding a particular branch, sacrificing it and prioritizing other growth. Getting rid of the dead stuff will make it easier to see what needs to be done with the living parts of the tree.
In the spring, you can spot dead wood because it’s not producing any buds. In the summer, look for branches with no living leaves. Dead wood may be dry and brittle or rotten and soft. Either way, you should remove it with your clippers, loppers, or saw. Do the same for any branches that are obviously succumbing to disease.
Make The Cuts As Clean As Possible
Jagged, uneven wounds take longer to heal and make it easier for pathogens to get a foothold in your tree. Always try to chop through a branch in a single smooth motion. If you’re ever in doubt about whether a branch is too thick for your clippers, switch to a larger tool. And make sure that you keep your blades well-honed. It’s a good idea to sharpen them after each pruning so they’re ready the next time you need them.
Between cuts, soak a rag with your disinfectant solution and wipe down the blades. That way, even if you cut through diseased wood, you shouldn’t transfer the germs to a healthy area.
Prune Japanese Maple Branches At An Angle
You don’t want to leave flat stubs on your tree, especially if the branch you’re removing was growing upward. Flat cuts more easily accumulate water, which can encourage a fungal infection. Instead, cut at a 45-degree angle, creating a slope to allow moisture to run off. If possible, leave the open end facing down.
Don’t Trim Past The Collar
It’s best to make your cuts relatively close to avoid leaving an unsightly stub sticking out where you’ve removed a branch. However, you should never cut so close that you damage the branch collar. This is the ring of slightly thicker wood at the very base of each limb and branch.
This fatter section contains important tissue for healing, so if you damage it, you’re massively increasing your Japanese Maple’s risk of infection. Ideally, you should cut just past the collar. If that’s not possible, err on the side of cutting too far out.
Prune a Japanese Maple From The Bottom Up And The Inside Out
In general, it’s safer to remove lower branches than higher ones. And branches that are growing inward or crossing the midline of the tree tend to be more expendable in terms of the overall look of your Japanese Maple. That’s why it’s best to start pruning at the bottom and clean up the interior before moving up and out.
Circle around the tree as you go. If you can, go around it at least twice before you’re done. This will help you keep your maple’s overall shape in mind instead of over-pruning specific sections.
Don’t Over-Prune a Japanese Maple
These trees grow fairly slowly, especially when they’re mature. If you’re in doubt about a specific cut, wait and revisit it next season. You should also never remove more than ⅓ of your Japanese Maple’s foliage in a single year. It’s often a good idea to snap a quick picture of the tree before you get started so you can refer to it as you go. Take frequent breaks to step back and take in the tree as a whole.
Thinning: How To Prune a Japanese Maple For Visibility
Thinning your Japanese Maple has two goals. Number one: it lets more sunlight and air into the canopy. Number two: it makes it easier to see the intricate branching structure of your tree. This is particularly important for “weeping” Japanese Maples, which can develop a dense shell of foliage that hides their limbs.
Here’s how to thin your Japanese Maple:
- Start small. Begin with shorter, thinner branches and see if removing a few of them does the trick. You can always cut more later.
- Remove “fishtails”. Look for branches that split into three smaller twiglets at the end. When you find one, clip out the central branch, leaving a “V” shape.
- Get rid of crisscrossing branches. It’s a health risk when two branches cross so tightly that they rub together. Remove one branch to let the other breathe.
- Remove twiggy growth. Mature Japanese Maples often sprout small clumps of twigs along their limbs that do little for the health or visual appeal of the tree. You can safely remove them.
- Create a “veil”. This technique is for drooping Japanese maples. The idea is to clip some of the smaller, lower branches on each limb, leaving the higher ones in place. Done right, the remaining branches rise up while their leaves drape down in a graceful curtain.
In practice, you’ll probably have to start thinning more or less at random. Pick a spot where the canopy looks too dense and make a few cuts, going by instinct but referring to the guidelines above. Then shift over to the next overgrown spot and make a few cuts there.
After you’ve made a full circuit around your Japanese Maple, step back and take a look. If the tree looks pretty and you can see the branches more clearly, you’re probably done.
Shaping: How To Prune a Japanese Maple For Structure
Japanese Maples grow beautifully even when left alone. But sometimes a few judicious cuts can really make them shine. Here are a few widely-accepted styling tips:
- Remove inward-growing branches. Branches projecting inward instead of out to the edges tend to create clutter. Leave a few if you like a slightly chaotic look, but otherwise, get rid of them.
- Thin out duplicates. Do you see two branches right next two each other growing in exactly the same direction? They’re redundant, adding nothing to the shape of your Japanese Maple. Prune one away to give the tree a more defined figure.
- Aim for layers. Try to pick out and accentuate distinct layers of branches and leaves. Prune away branches growing up into the layer above or down into the layer below.
- Pay attention to directionality. To emphasize a tree’s upright growth habit, you can take out branches that are growing downward. For a stronger weeping shape, remove growth that’s pushing up.
- Trim the central leader. This optional technique can encourage an upright-growing Japanese Maple to form multiple trunks. When your tree is still fairly small, clip back the uppermost shoot to a pair of branching buds. Note that this tends to slightly reduce the mature size of your maple.
- Accentuate the central leader. The opposite of the previous technique, this method produces a more conical shape with a thick central trunk. Simply prune away any large shoots that seem to be competing with the central leader. Do this if you want your tree to develop a more “tree-like” shape.
- Limb up. Removing some of the lowermost branches creates more room near the base. This can be good for Laceleaf Japanese Maples, which sometimes trail down to the ground and wind up looking more like a Tribble than a tree.
Reduction: How To Prune a Japanese Maple To Control Size
Pruning is not the most effective way to keep your tree from getting too big for its space. The best option is to pick a Japanese Maple variety that’s naturally inclined to stay small. But periodically trimming back some of the longest branches will help keep it to the lower end of its size range.
Here are some tips for reduction pruning on a Japanese Maple:
- Don’t cut too much at once. This is always good pruning advice, but it goes double when you’re cutting the crown of your tree. Never “top” your Japanese maple by hacking the whole tree back to a lower height. Limit your pruning to 20% of the crown in one year.
- Prune back to thick side branches. When shortening a limb, make sure the next side branch after the cut is at least ⅓ of the diameter of the part you’re cutting away. If it’s ½ the thickness or more, that’s even better. If it’s not thick enough to become a new leading branch, the tree will ignore it. Instead of extending the side branch, it will form a dense knot of twiggy growth at the stump.
- Redirect instead of lopping off. It’s best not to keep chopping a limb back to keep a Japanese Maple from crowding a structure, walkway, etc. Doing this repeatedly may produce a stump covered in whippy twigs. Instead, try cutting back to a side branch that’s pointing in a different direction. Over time, you may be able to “steer” the tree away from whatever it’s intruding on.
Final Thoughts
The advice above may seem like a lot to remember. But the most important takeaway is that you should prune a Japanese Maple with a “less is more” mindset.
It’s rare for these trees to develop serious issues from under-pruning. Go slowly, consider every cut carefully, and trim to emphasize the tree’s natural shape rather than modify it. This should result in a healthy and lovely Japanese Maple.