They don’t send out big blossoms to herald the arrival of spring, but Japanese maples have their own way of celebrating the end of winter.
Instead of flowers, they offer up colorful leaf buds and foliage in hues that are rarely seen on other trees.
Go ahead and try to convince me that ‘Oridono Nishiki’ leafing out in spring isn’t every bit as beautiful as a flowering cherry. I won’t even hear it!
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But gardening can be a heartbreaking endeavor. Things can go awry, and instead of marveling in the colors and textures of our favorite Japanese maple, we end up staring at pathetically bare branches.
In our guide to growing Japanese maples, we cover how to cultivate these dramatic trees in your landscape.
This article focuses on what could be causing your Japanese maple not to leaf out.
Why Japanese Maple Fails to Leaf Out
Before you start trying to figure out what the problem is, you need to confirm if the bare branches are dead or not.
I’m assuming you’ve examined the branch carefully to look for any leaf buds that are forming but that haven’t emerged yet.
If you don’t see any of these, take a sharp knife and peel back the bark. You can even use your fingernails if you have long, strong ones.
Is the wood green or tan? Does it feel moist if you touch it? Try poking a fingernail into the cambium. It should have some give. Or is it hard and dry? If it’s the latter, the branch is dead.
If you bend a branch, is it pliable or does it break? A branch that breaks easily usually indicates that it’s dead, as well.
Any dead branches, regardless of the cause, should be pruned off. If only part of the branch is dead, prune back to the first sign of growth and cut just in front of a leaf node.
If by June your tree isn’t showing any signs of life, it may be time to dig it up and toss it out.
Some trees will send up new growth from the roots and you’ll have a lovely Japanese maple bush in a few years. But typically, if this is going to happen, you’ll see new growth by summer.
Let’s talk about some common reasons why Japanese maples fail to leaf out:
1. Drought
Drought stress can be a tricky issue to diagnose. The soil might feel fine right now, but if the tree experienced drought at any point in the past year, it can cause limb death or even kill the entire specimen.
And confusingly, it can often take a few months for the damage to be revealed. Drought stress can also impact when the tree leafs out.
So you can’t just check the current soil moisture to determine if drought is the problem.
But if you can recall a particularly hot and dry period in the previous fall, it’s entirely possible that the tree was stressed enough to kill part or all of it, and the damage just didn’t show until it was time to leaf out in the spring.
Or budding may be delayed as a result of moisture stress and lack of nutrient stores from the previous year.
All you can do is cut off the dead parts and support the tree going forward so that it can produce new growth. If the entire tree is dead, you’ll obviously need to cull it.
2. Late Freeze
If you’ve ever grown a fruit tree, this is going to sound familiar.
As the tree starts to develop leaf buds, they’re susceptible to damage if there happens to be a late freeze. A late freeze can kill the emerging leaf buds.
Japanese maples aren’t extremely sensitive to frost, but a hard freeze that lasts a while when the buds are developing might be enough to kill them and prevent the tree from producing foliage.
Most maple trees will develop new buds after the initial ones are killed. Others might shed the branch. Either way, there isn’t anything you can do but support the tree.
3. Root Rot
Japanese maples love moisture, but not too much. Phytophthora root rot is caused by oomycetes in the Phytophthora genus.
The pathogens need water to move and reproduce, so they thrive in soil with lots of moisture.
Symptoms will depend on how far the disease has progressed and what time of year it takes hold.
In the early stages of the disease, the older part of the branches will leaf out, but young tips won’t, as they suffer from dieback. As it progresses, entire branches might die.
The tree might also leaf out late or appear to be stunted and sad.
It’s kind of hard to be absolutely sure you’re dealing with root rot because the symptoms can be kind of nebulous.
The easiest way to tell what’s going on is to dig down and look at the roots. There will be no feeder roots, which are the smaller, more delicate roots.
In advanced stages, the larger roots will be soggy and black.
You’ll need to drench the soil in fungicides to kill the pathogens. There are several options that will work.
Copper is a good place to start, but more advanced cases need a product that contains hydrogen peroxide and phosphorous acid or Bacillus subtilis.
Serenade ASO has proven to not only prevent but also kill Phytophthora pathogens.
You can find Serenade ASO available at Arbico Organics.
Follow the manufacturer’s directions closely and your tree should be on the road to recovery in no time at all.
4. Verticillium Wilt
If part of the Japanese maple is dead while other parts appear to be perfectly fine, it’s possible that your tree is suffering from verticillium wilt.
Caused by the fungus Verticillium dahliae, this disease restricts the ability of the tree to absorb and move water.
It can kill an entire tree, but you’ll typically see portions of the tree die before the entire specimen succumbs.
So, if half of your tree is leafing out and the other half is bare, it could be vert.
The causal pathogen lives in the soil and attacks hundreds of garden species, so it’s hard to avoid.
If your tree is suffering from this disease, you have two options. You can pull it entirely or you can cut off the dead parts and burn or dispose of them in the trash. Don’t compost them.
Sometimes a Japanese maple will survive with the disease and you can just trim off the infected bits. Other times, the entire tree will die, quickly or slowly.
There’s no way to tell how it will go other than to just let things play out.
You can send in a portion of the tree to your local extension office for testing to confirm the disease, or you can cut off a dead branch and look at the cross section. Dark or black rings are a sure sign of verticillium wilt.
You don’t need to remove the tree for fear of the disease spreading to other plants if it’s still hanging in there. The disease is already in your garden.
But you should always clean your tools – like shovels and pruners – between work to avoid introducing the pathogen to other plants.
Learn more about this and other Japanese maple diseases here.
5. Winter Damage
Japanese maples are susceptible to winter damage from freeze and thaw cycles.
The cells in the tree freeze when temperatures are below 32°F and then thaw out when conditions are warmer.
This happens over and over, gradually draining the tree’s ability to withstand future freezes.
Of course, heavy snow and wind can also break branches. But this sort of damage is more obvious.
Think back over the winter. Did you have a lot of freezing and thawing? It could be that your tree sustained damage that killed the branches, preventing bud formation and leaf growth.
Learn more about Japanese maple winter damage here.
Don’t Leave Us Hanging
Sometimes being a good gardener requires some clever detective work. The missing leaves on a Japanese maple are an obvious problem, but the cause can be a bit of a mystery.
Consider keeping a gardening journal just in case you need to figure out a problem like this in the future.
Knowing that you had a rot-causing rainy autumn or a severe drought in late summer can tip you off to the source of your woes.
Did you figure out the reason for your leafless Japanese maple? What did you do to resolve it? Let us know in the comments section below!
And for more information about growing Japanese maples, add these guides to your reading list next:
