Japanese Maples are wonderful landscape trees, but it’s possible to have too much of a good thing. You might have realized a tree is planted too close to your house, walkway, or power lines. Or it may simply be getting too large for the garden it’s growing in. Can you hard prune a Japanese Maple to cut it down to size? We’ll look at the limitations of pruning for controlling your tree’s growth and explain your best options.
It’s almost always a bad idea to hard prune a Japanese Maple and cut all its limbs back at once. This practice, also known as “topping”, is a severe shock to the tree and threatens its long-term health. A hard-pruned Japanese Maple may also never recover its graceful shape. It’s better to strategically reduce the crown by cutting back to slimmer branches where appropriate.
There are a few cases where it may be necessary to take off a significant amount of your Japanese Maple’s foliage. If you can, it’s better to spread this pruning out over several years. Tending to a Japanese Maple is a lifelong process that requires patience and careful judgment to get right. See below for the best methods to cut back your tree.
Why You Might Want to Hard Prune a Japanese Maple
The main reason gardeners and homeowners are tempted to prune Japanese Maples aggressively is due to space limitations. Because these are slow-growing trees without invasive root systems, it’s possible to misjudge how close to other trees or structures they can grow. A Japanese Maple that’s fairly compact when planted could be bumping against your second-story windows 20 years later. In some cases, this is the result of a previous homeowner’s mistake rather than your own error.
Another possibility is that you think the tree’s overall shape is ugly, but you see some potential in it.” Japanese Maples have such beautiful foliage and such graceful limbs,” you think. “If I can just cut this one back enough, I can get it to grow back beautifully.”
We have some bad news — there’s only so much you can do about a mis-sited or badly shaped Japanese Maple. Chopping back the tree’s major limbs won’t get the results you want.
The Trouble With Topping a Japanese Maple
Why can’t you just hard prune a Japanese Maple to make it prettier? There are several reasons, which we go into more detail about below.
Hard Pruning Stresses Your Japanese Maple
Trees can’t cry out in pain, but they do react strongly to having their limbs chopped back. Remember, your Japanese Maple relies on its foliage to produce energy. The loss of most of its established growth will essentially starve the tree until it can grow back some leaves.
In an effort to fix the problem, it will often send out a rapid flush of long, thin, whippy growth. These are known as “water sprouts”. Creating them can deplete most of your Japanese Maple’s stored energy. This weakens it and leaves it vulnerable to environmental threats and disease. There’s also a risk of sun damage to the bark now that you’ve stripped it of shade.
A Hard Prune Leads to Ugly Growth
Japanese Maples take a long time to develop. It’s typical for them to need 15 or 20 years to go from a skinny sapling to a mature, spreading tree. Hard pruning is an attempt to shortcut that process, and it won’t work. When you cut big branches back to stumps, the new growth that emerges isn’t thick and robust like mature limbs. Instead, it’s the slender water sprouts we mentioned above.
These new stalks look out of place next to the thick stubs of the bigger branches. They also tend to grow in tight bunches covered with leaves. The result is a thick trunk with a short, dense bush of foliage at the top. They’re often called “lollipop trees” by seasoned arborists, and they’re a far cry from the elegant, gnarled limbs of a mature Japanese Maple.
Topped Japanese Maples Are Unstable
Those new shoots also aren’t anchored to the main trunk of the tree. Instead, they’re attached to the outer layers of the severed limb. In time, they might grow into longer, more pleasant-looking branches, but they’ll never be as secure as the older limbs. They’re much more likely to snap off under pressure from strong winds or heavy snow.
On top of that, bigger cuts are harder for the tree to heal properly. There’s a much higher chance of rot, disease, or pests moving into the wound, further weakening the damaged limb. This is only exacerbated by the energy deprivation that results from losing lots of foliage, and the weakened tree is less able to fight off infection.
The combination of all these problems means that if you hard prune a Japanese Maple, there’s a very good chance you’re drastically shortening its lifespan.
How to Prune a Japanese Maple for Size Reduction
Does all this mean that your only option for dealing with an overgrown Japanese Maple is to cut it down? Not necessarily. Judicious removal of certain branches can help you reshape the tree and size it down slightly. This practice is known as crown reduction, and it’s much better than hard pruning a Japanese Maple. Here’s how it works.
Prune in the Winter
In some cases, pruning a Japanese Maple in the spring or late summer can be a good idea. However, if you’re going to cut it back substantially to reduce its size, always wait until it’s gone dormant for the winter and lost its leaves. This lessens the shock to its system.
Cut Back to Secondary Limbs
Start with the limb that’s causing the most trouble. Instead of cutting back willy-nilly to the length you want, look for a secondary branch along its length that’s heading in a better direction. You’ll be cutting back to the spot where this branch splits off, making it the new leader of the limb. This should be less stressful for your Japanese Maple and less likely to result in water sprouts.
Make sure the new leader is as large as possible. At a minimum, it should be one third of the diameter of the limb you’re removing. Bigger is better if you can find a thicker limb that’s not going to poke somewhere you don’t want it.
Prune Your Japanese Maple Carefully
Always make your cut just past the branch collar, the slightly swollen ring around the spot where the branch emerges. If you cut into the collar, it will be harder for your Japanese Maple to seal up the wound.
If the limb you’re cutting is large and heavy, cut a couple of notches a few inches away from the trunk. They should be a few inches apart, each one slicing about halfway through the branch. One notch goes from the top of the branch down, the other from the bottom up. The lower notch should be closer to the collar.
After you’ve notched the limb, make your final cut at the branch collar. This way, if the limb snaps as you’re sawing through it, it should break off at the notches instead of tearing all the way off the tree and peeling bark from the trunk.
Disinfect your loppers or pruning saw before each cut. Wipe the blades down with rubbing alcohol to keep mold and viruses out of the wound.
Reduce Width as Well as Height
In many cases, you’ll have better luck keeping your Japanese Maple a little skinnier than making it shorter. That may be all you need — unless the tree is growing straight up into a power line, problems with its size are usually about lateral branches sticking into spots where they don’t belong.
Regardless of your final goal, you should avoid simply cutting off the uppermost limbs and leaving the lateral ones alone. This often leads to an odd, squashed appearance that won’t look good in the long run.
Less Is More
Avoid cutting off more than 20% of your Japanese Maple’s branch mass in a single season. If you can do less than that, do less. A few strategic cuts once a year can often gradually bring a Japanese Maple back to a more manageable size over time.
You Can’t Always Prune a Japanese Maple to the Size You Want
The crown reduction technique we’ve just described is much better than topping a Japanese Maple, but it still has its limits. As a rule, you should assume this method can keep your tree 10-15% smaller than it would normally grow. Instead of counting on pruning to keep a tree in check, it’s best to start with a small variety of Japanese Maple.
If you’re dealing with an established maple that’s massively overgrown for its placement, it may be time to consider removing your tree. You could still try to cut it back and cross your fingers. But in most cases, when you hard prune a Japanese Maple, you’re simply stressing the tree out for a short-term reduction. If it lives, it will eventually grow back to about the size it was before. Sometimes it’s best to simply cut your losses.
Final Thoughts
Never hard prune a Japanese Maple unless your only alternative is to cut it down completely. Even then, you should give serious thought to doing exactly that and saving yourself some time. If you can get the tree to the size you want it with a well-placed crown reduction, your Japanese Maple will be much better off in the long run.