How to Prune Laceleaf Japanese Maples

A laceless Japanese maple often forms the centerpiece and a main focal point of a well-designed garden.

The Wonderful and Exotic Laceleaf Japanese Maple

Laceleaf Japanese maples are some to the most graceful and elegant trees that one can plant the home garden. Often, having one in a prominent location for all to see is a highly desired status symbol because of their elegance. Laceleaf maples may even be considered to be at the top tier of all garden tree—the aristocrat of ornamentals, that is, if they’re well pruned. If not, they can look more like a scruffy, derelict mess!

Laceleaf maples are from the dissectum group of Japanese maples, and are so named because of their deeply dissected or incised leaves from one side of the leaf petiole or stem to the other giving them a lace-like appearance, hence their name. To add to the perfection of these lacey beauties, they generally have seven lobes. It is a deciduous tree that forms a mounding, shrubby shape and can be a single to multistemmed tree with cascading branching and a semi-weeping habit.  The lacelef maple is generally slow-growing and typically reaching no more than four to six feet in height with a wider crown spread. 

Due to the popularity of the laceleaf maple over the centuries,  horticulturalists have developed more than 2,000 varieties with all variations of leaf colors and configurations. The bright reddish colors that many laceleaf maples turn in the autumn can be real eye-catching head turners.  

The Japanese maples originate from the hills Japan, Korea, China and into eastern Mongolia and southeast Russia. The botanical name for the Japanese maple, Acer palmatum, is credited to the Swiss botanist and doctor Carl Peter Thunberg who lived in the late 1700s. Acer  is the botanical name for maple, and palmatum refers to the hand-like look of the leaf.

The Japanese name for the Japanese maple is momiji meaning “the hand of a baby.” 

Japanese Maples Vs. Laceleaf Japanese Maples

There are several broad categories of Japanese maples from which the more diminutive laceleaf variety derives.

  • Upright Japanese Maples: Under the moniker of “Japanese maple” (the upright variety), there are hundreds of cultivars that come from three main maple varieties:

Acer palmatum. This is the largest family of Japanese maples. There are more than 1000 cultivars of acer palmatum worldwide. The word cultivar is a blend of the two words cultivate and variety  and was coined as a botanical term in the 1920s.

Acer japonicum. This is a smaller family of Japanese maple with only a few varieties.

Acer shirasawanum— This is another smaller branch of the Japanese maple family with only a few varieties.

  • Laceleaf Maples or the dissectum group of Japanese maples of Acer palmatum var. dissectum: Under the moniker of lace leaf (a.k.a. laceleaf or lace-leaf) Japanese (weeping, dome-shaped or cascading) maples, there are dozens of varieties for sale in nurseries. These trees are cultivars of the three main varieties of upright Japanese maples listed above. As such, they will have names, for example, like Acer palmatum “Red Feathers,” Acer shirasawanum “Green Snowflake” and so on. 

Other Characteristics of Laceleaf Japanese Maples

Not only are laceleaf maples known for the showy leaves, but they have flowers as well. Blooming in the spring, these maples have small reddish flowers that occur on stalked, umbrella-shaped clusters. The individual flowers have five red or purple sepals and five whitish petals. The laceleaf maple is monoecious plant meaning that it contains both male and female flowers on the same tree.  In other words, it is self-pollinating.

The flowers then give way to the fruit, which are two-winged seed, often called helicopters. The technical term is samara. These samaras ripen in late summer to early fall and are green to red in color and one-half to three-quarters of an inch long, maturing to reddish brown.

The foliage of the laceleaf maple is feathery or lace-like with leaves that are opposite each other on the stem and are two to five inches long and wide with seven, nine or eleven lobes. Leaf color is dependent upon variety with colors ranging from green to crimson with outstanding yellow, orange, or red fall color. Leaves emerge in the early spring.

When to Prune Laceleaf Maples

Because of the high-priced value of laceleaf maples, there is a general idea among amateur gardeners that it takes a special skill to prune them. Many times, laceleaf maples are left unpruned for fear of causing them irreparable damage. While this may seem like a legitimate concern among novices, over the decades, I have seen very few examples of irreparably pruned laceleaf maples. Like a bad hair cut, it will grow, though it may take a few years. A healthy Japanese maple tree want to grow, and grow it will! It’s simply a matter of working with it and training it to grow properly. Here are a few tips on how and when to prune laceleaf maples.

Before pruning…

The general consensus among pruning experts is that Japanese maples can be pruned anytime of the year. This will depend on the climate where you live, though and the health condition of your tree and the desired effect you want from your tree. That fact is that in Western Oregon, where I live and work, because of the mild climate, we’re pruning Japanese maples all year long without hurting them. I many clients whose maples I have pruning year-after-year for years.

What are the benefits of pruning at certain times of the year over other times? There are a few. For example, it’s easier to prune deciduous trees like laceleaf maples in the winter when the leaves are off, since it’s easier to see the branching structure. 

If my client wants an extremely manicured look to their maple, I recommend pruning it in the summer after the spring growth has occurred. This way, they tree will look well-manicured until it starts pushing out new growth the next spring. The main caution with summer pruning is not to over-prune the top of the tree’s crown, so that the sun’s rays penetrate unhindered by a top-layer of leaves and hit the tree’s main trunk or branches potentially resulting in sunscald where these branches dry out and crack open becoming susceptible to disease and rot.

For my clients who want a less manicured and a more natural, fountain-like appearance to their maples, I recommend pruning their maples mid-growing season (in May or June). By pruning them hard at this time of the year, plenty of new growth will still come out before the summer heat hits and the plants stop growing. This will give the trees the more natural, fountain spray and less manicured look, which some clients prefer.

After pruning.

The Tools to Use

I am very particular about my pruning tools, since I take pruning seriously. It’s what I do for a living; therefore, I use only the best tools. I have been using a Swiss-made Felco hand pruners for more than 40 years. These are not inexpensive, but are best pruners in the world used by most professionals, and a they will last a lifetime if properly cared for. Replacement parts are readily available and they’re easy to sharpen. 

You will also need a small hand pruning saw. I use the Japanese made Silky hand saw with fine (as opposed to course teeth), so that I can make clean cuts wihtout tearing the tender tree bark. 

Small lopping shears (or loppers) can be helpful as well, although I find that my pruners and saw are sufficient for all of my pruning jobs, big or small.

Pruning Tips for Laceleaf Maples

The type of artistic or aesthetic pruning that I, as a professional aesthetic pruner, do can’t adequately be taught in books or an article such as this. I have to teach this skill and art form in person. 

However, there are certain basic principles that can be learned from books, but each tree is unique, and therefore it’s difficult to apply the ridged and idealistic examples taught in a book to real a real life situation. This is true of any artistic activity whether painting, drawing, sculpting or whatever. The skill and art of pruning has to be taught by a master-pruner to his disciple through hands-on demonstration and learning. Videos are more helpful in teaching the skill of aesthetic pruning, but, again, each tree and situation is different and presents its own challenges and unique circumstances. Only the master pruning artist can mentor his students on the art of navigating these waters on a case-by-case situation until the student catches in his or her mind and heart the science and art of aesthetic pruning. 

Aesthetic pruning is one thing. Pruning in a Japanese style can be quiet another thing. They are related, but different. The latter takes aesthetic pruning to a higher level or art form.

The most basic principles of Japanese pruning of garden trees (called niwaki) derive from the seven artistic principles of Zen Buddhism. These include asymmetry, simplicity, austere sublimity, naturalness, subtle profundity, freedom from attachment and tranquility. “The Japanese term wabi and sabi sum up this elusive collaboration: the raw purity of nature (its beauty living side by side with imperfection and harsh reality) is combined with man’s creative and spiritual intervention, refining nature down to an essence” (Niwaki—Pruning, Training, and Shaping Trees the Japanese Way, p. 23, by Jake Hobson). These art principles of Zen Buddhism inspire my pruning of Japanese maples. 

When I feel that I need an additional shot of inspiration, I make take field trip up to the Portland Oregon Japanese Gardens to study the maples (and other trees and shrubs) there. This garden is the top-rated in North America, and by some accounts the top in the world outside of Japan. If you live in the Portland area, visit the Portland Japanese Gardens and get inspired. I learn something new every time I go up there!

The Dos of Pruning

Now here are my specific tips for pruning a laceleaf Japanese maple:

  • When I approach a laceleaf maple (or any tree or shrub that I’m about to prune), I first walk around the tree to study its branches, silhouette and overall shape and structure. Every tree has a geometric shape and a direction or pattern in which the branches flow. Determine what that pattern is, and work to remove anything that violates or runs cross grain to that pattern. Let the tree “talk” to you. It will tell you how it wants to grow. Go with the flow of it.
  • Next, I get a vision in my mind of what I want the tree to look like afterwards. Again, let the tree “talk” to you. How does it want to grow? Work with that. Unless you’re doing bonsai and are intent on force-pruning the tree to grow in arbitrary ways, work with the tree and let it help you to determine how it wants to grow.
  • Make proper pruning cuts. Never flush cut a branch to the trunk. Always cut just outside the trunk-branch bark collar, which is the wide protrusion extending from the trunk from which the branch protrudes.
  • The first thing I do is to remove any dead, diseased, deformed branches first. They have to go. Remove the clutter of dead branches, and then now you can begin to work with the live branches that are left.
  • Next, I remove much if not most of the wispy new growth found in the center of the tree unless you need it to fill in a gap in the crown. If so, leave the best shaped and formed branches and begin to train them, so that can eventually grow into a larger branch.
  • Keep this rule of thumb in mind: prune from the inside out, and the bottom up. You may need to crawl onto your back under the tree and prune from the inside of the tree if it is overgrown and overly thick.
  • Remove any sprouts that may be growing below the graft line on the tree trunk
  • Begin removing any larger branches that you don’t want. This includes any crisscrossing, duplicating, rubbing branches or any running cross grain to the general direction the tree wants to grow in. By removing larger branches first, you won’t be cutting on branches that you’ll just end up removing later. This is a waste of time and energy. Removing rubbing branches reduces the chance for disease to enter through wounds in the bark. If two branches are growing parallel to each other, remove the less desirable one. By removing crossings, parallel and duplicating branches, you are effectively opening up the tree to allow air and light to penetrate interior of the tree’s crown, thus promoting a healthier environment in which the tree can grow. This creates a more open, symmetrical and aesthetically pleasing look.
  • Consider remove branches that are growing inward or in the wrong direction unless removing it leaves a large gap in the crown. It that is the case, leave the branch. You have to work with what you have; it’s not a perfect world!
  • If possible, separate the branches into layers. Establish planes and layers of branches. Not only does this create a more three dimensional look, but helps to make the tree look more interesting, older and more  mature.
  • Thin the entire crown judiciously to open it up and to allow one to see the beautiful structure or architecture of the tree and to allow for air circulation (this helps to reduce fungal pathogens invasion into the tree), and to allow for sunlight penetration so interior leaves can grow and photosynthate.
  • After you’ve worked on the interior of the tree for a while, step back and work on the overall outer shape of the tree. Also, every so often, step back and look at the tree from a distance as you’re progressing along. You have to come out of the forest form time to time to see the trees, or the overall perspective. Walk around the tree and view it from all angles to make sure you’re pruning it in a balanced way.
  • What is your main focal point? What is the main vantage point or angle from which the tree will be viewed by the most number of people? Prune with that in mind.
  • Try not to remove a limb that is greater than half the diameter of the tree’s trunk. In fact, I would probably stop with a quarter to a third with older trees.
  • Create a thin layer of small branches over the top of the tree to prevent the sun’s ultra-violet rays from scorching the interior main branches and causing irreversible sunburn or sunscald to them.
  • Most laceleaf varieties have weeping and twisting branches that form a dome shape if left to grow on their own. From one of these branches, you can also stake up a leader branch vertically and turn it into a new trunk. Allow the secondary branches to weep down. By training a branch upward, this will give the tree more height. 
  • Raise the tree’s crown or canopy by removing branches that are dragging on the ground to at least six inches or more above the ground.

The Don’ts of Pruning

  • Don’t be afraid to prune laceleaf maples. They’re not as fragile as they appear. If you make a mistake, like a bad haircut, it’ll grow back and you can do it right the next time.
  • Don’t overprune the top of the crown, so that no small branches are covering the main trunks. The tree needs a covering of small branchlets over the top its crown to prevent sunscald on the main trunks. It’s the same reason thin-haired and bald people wear hats in the sun.
  • Never shear a laceleaf maple! Shearing these beautiful trees ruins their natural appearance and encourages leaf growth only at the end of the branches. Furthermore, this type of shearing blocks air and light from entering the canopy, making the tree more susceptible to disease problems and dieback. Resist the urge to shear your laceleaf maple into a ball or a doughnut.
  • Never leave stubs. Always make proper pruning cuts. Don’t flush cut a branch to the trunk, but just outside of the branch bark collar.
  • Some pruners say to avoid pruning in the spring when the sap is flowing, although this won’t kill the tree if it has plenty of water and soil nutrients and is healthy. Generally, for the overall health, of the tree, it’s best to wait until after the growing season is done. This occurs when the hot summer has started and the plant has gone into its summer dormancy. In reality, I have pruned laceleaf maples every month of the year,  including many in the spring year-after-year and in the middle of the growing season, and I have never seen it damage a maple if the tree is healthy and well-watered. 
  • Resist the temptation to strip out the interior of the tree of all small branches. By judiciously leaving select branches on the interior of the crown, this creates multiple dimensions to the tree, thus promoting a more three-dimensional and hence a more interesting looking tree.

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