Winter can be hard on all of us.
Sure, the snow can be beautiful and there’s a certain magic to the dormant season, but sometimes those heavy snows and hard freezes can do a number on our gardens.
For Japanese maples in particular, adverse weather conditions can cause some significant dieback and other damage.
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If you’ve ever dealt with dieback before, you know that it can be mystifying. Why were your trees fine one winter, and decimated in another?
In this guide, we’re going to discuss what causes this common problem and what you can do about it. Here’s everything we’ll cover up ahead:
What You’ll Learn
Strap on those mittens and put on your warmest coat, because we’re heading into the freeze.
What Causes Winter Damage in Japanese Maples?
It’s not the cold that causes the most damage to Japanese maples. It’s freezing followed by thawing that happens over and over again throughout the cold months.
As the cells inside the plant freeze, thaw, and refreeze, it reduces the tree’s ability to naturally withstand cold weather.
Think of this as something along the lines of the antifreeze in a car, if it were gradually draining out.
At some point, there isn’t enough “antifreeze” to keep things protected in your plants either, and that leads to problems.
This causes damage and sometimes death to stems and branches. It can also damage or kill the developing leaf buds.
Winter damage may also be caused by extreme wind, heavy snow, or freezing and thawing soil, in addition to repeated fluctuations in the air temperature. And it can be caused by dehydration as well.
While we might not typically think about our trees and other perennial plants needing moisture during the cold months, if you have an unusually dry spell it can harm your trees.
Trees that leaf out earlier in the spring than other types are particularly susceptible to damage because they may start emerging from dormancy before the weather is ready to cooperate.
A late freeze can kill all those emerging leaf buds. Young trees and those in containers are particularly at risk. Trees in containers are more exposed to the cold, and the drying effects of the sun and wind.
You might think that dieback isn’t happening because your plant has been growing in the same location for decades.
Surely it’s fine, right? It must be something else. Just keep in mind that climates can gradually change over time and you can experience extreme weather events at any time.
Just because you’ve planted a type that is perfectly happy in your USDA Hardiness Zone, that doesn’t mean you won’t experience temperatures out of the norm.
What Does It Look Like?
There’s no point in looking for damage in the winter.
It’s really hard to tell the difference between signs of dormancy and injury, and who knows which stems may actually recover and which will give up the ghost.
Wait for the leaves to bud and form before you take action.
Then, look for dead branches, shriveled leaves, black stems, leaf drop, black or brown leaves, or broken branches. You should also watch for peeling bark.
Sometimes a branch will be alive but it won’t develop leaves in a particular year, so don’t use that as your only determining factor.
Try gently bending a branch before culling it. If it bends rather than breaking, and it’s the same color as the surrounding branches, it’s probably still alive.
Of course, any of these symptoms could also be related to something else, like a pest infestation or disease.
But if it’s only impacting one branch and the rest of the tree looks fine, you can usually chalk it up to winter damage.
If you had a particularly strange winter with heavy snow followed by sunny, warm days and surprise heavy freezes, that makes it all the more likely.
Dealing with Winter Dieback
I like finding clear signs of winter dieback more than discovering evidence of pests or diseases because it’s so simple to deal with. Just get rid of it!
Once you remove the dead parts, the tree will continue growing as if nothing happened… usually.
Clean off any dead portions using a clean pair of pruners or a saw. You don’t have to seal the cuts.
A big drawback here is that sometimes, removing these dead parts of the tree drastically changes its appearance.
If that’s the case, feel free to shape the rest of the tree as needed to try and bring everything back in balance. Don’t remove more than a quarter of the total aboveground growth – including the stuff that died – all at one time.
It might take a few years to get things back in shape, but you don’t want to contribute further stress to an already stressed tree.
If your Japanese maple has lost a significant portion of its growth, your best bet is to give it as much protection and support as you can to help it survive the strain and produce new branches.
Young tree trunks can be wrapped in white reflective guards to protect them from sunscald. Pick up 50 feet of three-inch wrap from DeWitt at Arbico Organics.
Protecting trees from damage in the cold months starts in the fall.
During the winter when the ground is frozen, you might expect your tree to stop losing water, but that’s not the case. Water still evaporates through a process called transpiration. And strong winds make this effect even more pronounced.
Give your trees ample water in the fall so they’re ready for the winter. This helps them to withstand the damaging effects of cold weather.
When I say ample, I don’t mean drown the poor things. Provide them with the recommended amount, but make sure you’re consistent about it.
You can also add a thick layer of leaf or straw mulch. Four inches piled around the root zone of your Japanese maple is fine, just don’t pile mulch against the trunk, since this can encourage rot and diseases.
Think of a donut shape instead. The center should be empty with a ring of mulch encircling the trunk.
Avoid heavy pruning, feeding, or overwatering in the fall. This encourages vigorous growth late in the season, which can lead to dieback.
Don’t Let Winter Put a Damper on Your Garden Design
In general, if you plant a Japanese maple in the right area and give it proper care, you won’t have to deal with too many issues.
But winter dieback is one of those things that is difficult to prevent or protect your plants from.
Sometimes you have to let nature do its thing. But if you follow the tips in this guide, you can minimize the impact it will have on your tree.
Did you discover signs of winter dieback on your tree this year? What are your plans for preventing damage in the coming year? Share your tips and advice in the comments.
Japanese maples are fascinating and storied trees, and it seems like there’s always something new to learn about them. If you agree, you might be interested in reading these guides next: