If you’re the proud owner of a maple tree, congrats on having such an amazing plant in your landscape! The brilliant foliage and fall color of various Acer species makes them true works of art!
However, what sets a maple tree apart from, say, a statue or painting, is that a growing maple is never quite finished.
Once you put down the chisel or paintbrush, the art you’ve created is generally complete and ready for display. But when an Acer goes into the ground, a gardener’s work is just beginning.
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Besides properly cultivating the maple tree and providing preventive care to keep it free of pests and disease, a gardener will need to prune an Acer as it grows and develops.
This promotes health and vigor, along with improved aesthetics – all of which keeps the plant looking and feeling majestic and vibrant!
Even though trimming is a pretty simple process, it may prove to be a bit more complex than it looks to beginners.
Anyone who just starts cutting away without the proper know-how could impair the health of their beloved tree. Luckily, learning the proper technique is easy, and we’re here to help.
In this guide we’ll provide a simple breakdown of maple pruning practices, without putting you to sleep along the way.
Not that what we’re covering here isn’t a captivating topic – when learning about a subject like Acer trimming, I’m left scratching my head, wondering how anyone could nod off. It’s practically the Adderall of horticulture topics!
Here’s everything we’ll cover up ahead:
What You’ll Learn
Why Prune a Maple Tree?
The prospect of intentionally causing injury to a plant can make any green thumb wince, especially when the plant in question is a gorgeous maple tree.
And since Acer species ooze sap from wounds more profusely than most other plants, pruning one really does feel like you’re making a living, breathing thing bleed.
So why would we ever do this on purpose? For a few reasons:
A tree must be free of broken, drooping, and otherwise damaged or weird-looking branches to look its best.
Beyond that, the growth habit of whatever species you’re cultivating may dictate when and how you opt to make your cuts.
For maples like A. rubrum that benefit from a bit of shaping to keep a tidy and manicured appearance, maintaining a strong central leader with branches at around 90-degree angles to the trunk is ornamentally essential.
Other species such as A. palmatum look better with a more natural trunk and branch structure.
Wounded branches and twigs are prime entry spots for pathogens and pests to enter plants. By addressing these vulnerable spots, infections and infestations are less likely to occur.
Cutting a maple tree back also thins it out a bit, increasing intra-tree airflow and helping to keep them sanitary and free of unwanted visitors like fungal pathogens.
In addition, thinning allows light to reach leaves that might be blocked from the sun’s rays in a crowded canopy. Plus, it strengthens the branches that you leave alone, which is pretty sweet.
As they grow, undesirable branches and twigs take up resources from the maple and the surrounding environment that could have otherwise been put to better use.
When you remove these freeloading plant structures, nutrients and energy won’t go to waste, and will go to other, more desirable shoots and structures instead.
Regular trimming also spurs new growth. The roots and shoots of a plant love to stay in balance, so when you remove shoots by pruning, the resources gathered by the now overpowered roots go towards shoot hyper-development.
What You’ll Need
There are a couple things you’ll need before you begin the project of cutting back these plants. If you’re an avid gardener or amateur arborist, chances are you have a lot of this stuff already. Beginners may need to buy or borrow a few necessary items.
Depending on the size of your specimen, you might need some vertical assistance such as a ladder in order to reach the highest branches. Be sure to work with a buddy for safety if this is the case!
Alternatively, it’s wise to consider hiring a professional arborist if the pruning needs of your Acer are beyond your reach.
Personal Protective Equipment
Safety is paramount, especially when sharp objects are involved.
Here’s a good place to start: safety glasses and work gloves. Safety glasses will keep sawdust, sticks, and sharp, pointy tools out of your eyeballs. A tough pair of work gloves will protect your hands from cuts and sticky sap.
If you’re looking for premium safety glasses, NoCry has some available on Amazon.
For a pair of heavy-duty puncture-resistant work gloves made with several layers of cut-resistant fabric to protect your hands, visit Garret Wade. These are available in blue or black, in three sizes.
These handheld tools are small enough to snip away twigs and small branches – perfect for small edits and finishing touches. Bypass pruners in particular will ensure the cleanest possible cuts, while also maintaining blade sharpness.
To purchase a set of carbon steel bypass pruners with a nonslip PVC grip, visit Gardener’s Supply.
With their tough, stout blades and leverage-manipulating handles, loppers are ideal for removing branches too large for hand pruners.
A heavy-duty set of bypass loppers with telescopic handles can be purchased from Garrett Wade.
A pruning saw is best used on branches that are too large for loppers, as well as on any competing trunks or leaders that you need to saw away. It combines heavy-duty sawing capability with the compactness necessary for fitting into tight spaces.
A handheld pruning saw with a 12-inch blade and wooden holster sheath can be purchased from Garrett Wade.
A pole saw is simply a saw blade on a long handle, which really extends your reach.
The handles of the longer models either collapse or disassemble into two or more sections, which makes the pole saw both lighter in weight and more convenient to store than pole saws with fixed-length handles.
Find a pole saw with a 15-inch curved cutoff blade, 25 feet of total reach, and a handle that breaks down into three separate pieces at Garrett Wade.
When cutting various shoots off of different plants, it’s really important to sterilize your tools in between cuts so any pathogens present don’t hitch a ride to new hosts.
A solution of water and isopropyl alcohol will get the job done – just make sure the alcohol is at least 70 percent of the mixture, with water making up the rest.
A fringe benefit of isopropyl alcohol is that it’ll help to de-sap your blades. Anyone who’s tried to open and close a pair of gummed-up pruners or loppers knows how helpful this is!
A bottle of 99 percent isopropyl alcohol is available from Solimo via Amazon.
When to Trim a Maple Tree
Diseased, broken, or decaying branches can be cut back whenever you happen to notice them. But keep the more involved sessions of shaping or thinning healthy green growth to once a year.
For the most part, deciding when to schedule your primary pruning sessions is a layup.
Trimming before that first flush of growth appears in spring will result in the most vigorous growth for most types of trees, so planning to do your work in late winter or early spring is a pretty good prescription… most of the time.
Maples, on the other hand, may require some more careful consideration.
Since they bleed so much sap from wounds, maple trees are a pretty notable exception. Because sap is so nutritious and life-giving to an Acer, cutting at standard pruning times could cause the tree to lose a lot of sap.
This sap loss may or may not be harmful, depending on the size and age of the tree. Sometimes sap loss is no big deal, while it can affect a maple’s health and vitality at other times.
Here’s a good rule of thumb to decide how to proceed: the greater a maple’s size and age, the better it can handle sap loss, and vice versa.
If your specimen is large and old, then you’re probably safe to trim during the traditional timeframe. But if your tree is small, young, or may be prone to excessive sap loss for some other reason, then hold off on pruning until summertime.
At this point in the year, growth has slowed and wounds won’t ooze as much sap, but it’s still early enough to avoid the wet, cold, and disease-promoting conditions of fall and winter.
How to Prune
We’ve laid out the motivations, the tools, and the timing behind this process. Let’s cover the actual pruning part now.
Here’s a helpful checklist to understand what you should prune, in order from greatest to least importance:
- Take off dead, sick, or injured branches right away, as soon as you see them.
- If choosing a central leader is applicable in young, poorly tended, or damaged trees, choose the strongest, most centered, and most vertical leader to keep, and prune away competing branches as needed.
- If two branches are crossing or rubbing together, this will eventually result in bark damage and injury. Choose the one with the branch-to-trunk angle that’s closest to 90 degrees, and cut away the loser.
- Remove low-growing branches so that the trunk below the canopy is emphasized, and encouraged to grow straight and strong.
- If a branch droops, points sharply upwards, or is otherwise nowhere close to a 90 degree angle from the trunk, prune it.
- If any branches are growing faster than the rest of the maple, cut them back to the length of the adjacent branches.
Pruning cuts should be made parallel to the trunk, and the cut stumps should just barely protrude from beyond the branch collar without cutting into it to avoid damage.
Non-parallel cutting angles allow for water to collect on the wound, which could result in disease.
If any branches that you wish to cut back are rather heavy, utilize the three-cut method by first making a cut one to two feet out from the trunk halfway up into the branch.
Next, make a complete cut a couple inches further out from the trunk. Finally, make the last cut slightly beyond the branch collar.
The three-cut method is great because the pruned branch won’t take a strip of bark or “heel” with it when it falls. If you need a vivid analogy, this is like when you aggressively pick at a hangnail and pull away a LOT more skin than you intended to.
Other than one-off pruning sessions of sick, dead, or damaged branches, all of the branches and twigs removed from the tree in one go should make up no more than a third of the plant’s total aboveground growth.
Any more, and the physical stress may prove excessive.
Prune from the top down, so you can pace yourself and avoid removing the maximum recommended growth prematurely.
This is basically a trick that forces you to regularly take a step back from the tree and look over your work to see if you’re rationing out your “pruning bucks” correctly.
Pruning from the bottom up, on the other hand, makes it all too easy to remove a third of the tree’s growth before you’ve even made it halfway up the trunk.
That’s a wrap on this guide, and it’s also a call to action: go prune your maple trees, people! As long as it’s the proper time, that is.
Pruning an Acer is quite empowering, especially if you’re used to leaving your landscape trees be and letting them do their own thing.
By maintaining a maple in this way, you take an active role in caring for and improving the tree’s appearance and well-being, which is pretty neat.
Questions or comments about any part of this guide can go in the comments section below. Others can really learn and benefit from what you have to say, so don’t be shy!
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