If you’ve ever wondered when to prune Japanese maple trees this article should prove very helpful. Japanese maples (Acer palmatum) are among the loveliest small trees you can add to your landscape, but people are often confused about their care, especially when it comes to pruning. There are so many different forms and cultivars, each one more beautiful than the next, but sadly, you can destroy their beautiful shape and foliage by pruning incorrectly. The good news is that by understanding how and when to prune Japanese maple trees, you’ll maintain their health and form. Read on to learn more about Japanese maple pruning and how to do it right.
Traits of Japanese maples
First, let’s begin with a brief overview of what makes Japanese maples so special and why pruning them incorrectly can negatively impact those special features.
With a graceful trunk, smooth bark, and sharply lobed leaves, the canopy of these small trees spreads into a distinctive shape. Some Japanese maple varieties, such as ‘Bloodgood’, are more upright with a spreading canopy. They grow up to 15-20 feet in height. While others, such as the many cutleaf or laceleaf cultivars (Acer palmatum var. dissectum), are typically smaller in stature and sometimes have a weeping or mounding form. There are dozens, if not hundreds, of cultivars of laceleaf Japanese maples. They can have leaves that are red, burgundy, pink, green, chartreuse, or any number of combinations and variegations thereof. Many have leaf colors that change throughout the seasons.
The good news is that to properly prune a Japanese maple, you don’t have to know what variety you have. No matter what kind of Japanese maple it is, the pruning needs, technique, and timing are the same.
How the form of a Japanese maple impacts its pruning
Before diving into the when and how-to of pruning Japanese maple trees, let’s quickly explore how the form of your tree will impact its pruning needs.
The goal is always to maintain the overall shape of the tree and its natural form, not to prune it into a tight, restricted ball or mound. These elegant trees have a branch structure that is so striking; why restrict their beautiful natural habit by shearing them into a forced shape? Most types of Japanese maple tree require very little pruning to maintain their form, if any at all. In this case, less is definitely more. That being said, there are indeed times when pruning Japanese maples is necessary.
Later in this article, I present a step-by-step guide to trimming Japanese maple trees, whether they are weeping or have an upright main stem. I’ll also share reasons why you may want or need to prune your tree. But first, let’s talk about the timing.
When to prune Japanese maple trees
To maintain the health of the tree, properly timed trimming is essential. Here are some easy-to-follow guidelines for when to prune Japanese maple trees.
- With Japanese maples, removal of dead stems and branches can happen at any time of year (more on this in a later section).
- The best time of year to prune any living wood is late fall to mid-winter (November thru January in Pennsylvania where I live). I don’t prune my Japanese maple any time after January. You’ll learn why in a moment.
- Unlike most other deciduous trees that are best pruned anytime during dormancy, maples should not be pruned in late winter.
- For the overall health of your tree, prune only when you absolutely need to. Pruning should not be done automatically or with the intent to force your Japanese maple into an unnatural shape (unless of course you’re growing it as a potted bonsai tree).
When NOT to prune a Japanese maple
Learning when NOT to prune a Japanese maple is just as important as learning when TO prune one. If pruning occurs in late winter, the wounds weep sap (this is why sugar maples are tapped in late winter; it’s when the sap is running). While this won’t kill the tree, it can potentially bring attention from insects and the pruning wounds can stay open longer, increasing the risk of pathogen exposure. Spring and summer pruning should also be avoided for the same reason.
Tools for pruning a Japanese maple
Cleanliness is key when pruning any trees, Japanese maples included. Use a pair of pruners (I prefer bypass pruners over anvil types), loppers, or a compact folding pruning saw, depending on the diameter of the branch you’re removing. All pruning tools need to be disinfected both before working on the tree and when pruning is complete to avoid spreading pathogens from one plant to another. Use a disinfectant spray or wipe, or dip the blades in a 10% bleach solution.
Never use long-bladed hedge shears or a motorized hedge clipper to shear a Japanese maple. Pruning should be slow and judicious, with careful consideration taking place before deciding where to make each cut (or if a cut needs to be made at all).
How to prune a Japanese maple: A step-by-step guide
First, remember that regardless of what tool you’re using for the job, a clean and proper cut is essential. Cut off the branch on a slight angle all the way down to the branch collar. Do not leave a stub behind (see photos). Next, follow these steps for proper pruning.
Step 1: Remove any dead branches
Begin pruning your Japanese maple by removing any deadwood. Be sure to check the tree’s underside. That’s where much of the deadwood is often found.
If you discover a completely dead branch, it’s always okay to cut it off, no matter what time of year it is. Not sure whether or not a particular branch is dead? Bend the outer tip of the branch with your hands. If it’s still flexible, it may not be fully dead. But if it easily breaks, it’s best to remove the branch entirely.
Step 2: Remove any damaged branches
Next, prune off any broken or damaged branches. The right cuts remove the limb a few inches past the point of the damage. The weight of snow and ice, or damage from animals or people, can break branches. These should be removed during the pruning process.
Step 3: Prune out any reverted branches
Occasionally there will be new growth on your Japanese maple that does not match the rest of its growth, particularly if the variety is variegated. These reverted shoots should be pruned off to maintain the variety’s unique form. In the case of a variegated Japanese maple, the reverted stems may be solid colored. For cutleaf varieties, the reverted shoot may have leaves that aren’t as finely serrated.
Step 4: Prune off any upright branches if the tree is a weeping type
For weeping types, from time to time a branch may shoot straight up into the air. Prune off these upright sprouts during the proper pruning time (late fall through mid-winter). Grafted varieties may also send up straight sprouts from the base of the trunk, below the grafting point. These should be pruned off, too.
Step 5: Remove branches that are overstepping their bounds
Knowing when to prune Japanese maple trees also involves making the difficult decision to trim back a branch if it is intruding on a sidewalk or driveway. Ideally, well-placed Japanese maples are far enough away from frequently used pathways to avoid having to prune them, but from time to time, you may have to cut off branches to make human travel easier.
Step 6: Trim out lateral branches but only if you must
Japanese maples have such a unique structure, with lateral branches that elegantly extend out from the trunk. A time may come when you’ll consider removing an entire branch or limbing-up the bottom of the tree to make way for mowers or to open up a view. I don’t recommend this type of pruning unless it is absolutely necessary. Japanese maples are much better off growing to their natural form.
When to leave well enough alone
I’ll end by saying that pruning Japanese maples is by no means necessary. If your tree has no damage and plenty of room to grow, you shouldn’t prune it at all. But if you must prune, be smart. Light pruning is all that’s needed in most cases. I hope you found this article on how and when to prune Japanese maple trees helpful.
For more great landscape trees, please visit the following articles:
- Trees with Peeling Bark
- The Blue Atlas Cedar
- Weeping Alaskan Cedar
- Trees with White Flowers
- Dwarf Hinoki Cypress
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