If this is your first year growing a Japanese Maple, you may be wondering what to expect. How do these trees change through the cycle of the seasons? Do Japanese Maples lose their leaves in the fall? And how will the colors change from season to season?
Yes, Japanese Maples lose their leaves in late autumn, though not before putting on a brilliant display of color. Winter dormancy typically lasts until early spring, with buds activating as the weather first warms up. Japanese Maple leaves often have beautiful and distinctive spring coloration.
It’s not a problem if your Japanese Maple is losing its leaves as part of its normal winter dormancy cycle. However, certain kinds of health problems can interfere with this process, causing your tree to drop its foliage out of season or fail to produce leaves on schedule. We’ll review the seasonal cycle of your Japanese Maple’s leaves and discuss what kinds of problems can interfere.
Autumn: Japanese Maples Lose Their Leaves Naturally
The typical time for a Japanese Maple tree to start shedding its leaves is the late fall. But first, they’ll usually display an incredible burst of color. These trees are renowned for the blazing reds, yellows, and oranges of their fall foliage.
The color change generally begins in late September or early October. As temperatures dip below freezing, the bold foliage will dry out and fade to brown. The leaves often begin dropping off in late November or early December.
That’s just a rule of thumb, though. The exact timing of your tree’s autumn transformation depends on the climate. An unusually cold fall may cause Japanese Maples to lose their leaves earlier in the season, while exceptionally mild weather could keep the foliage in place long after it shrivels up and turns brown.
Japanese Maples grown in containers typically begin preparing for winter sooner than those in the ground. The roots are less insulated, so these trees notice the onset of cold weather faster. Again, this isn’t a cause for concern; it’s just a Japanese Maple’s natural response to the climate.
Note that autumn is also when buds should form on your Japanese Maple’s new growth. At this stage, they’ll simply be small cone-shaped nubs. But those little points will sprout into new leaves next year.
Winter: Japanese Maples Go Dormant
Just as humans need sleep to recharge, deciduous trees like Japanese Maples need to shut down over the winter. Anything that disrupts this period of dormancy can pose problems for the tree’s health and growth. For example, it’s a bad idea to fertilize a Japanese Maple too late in the summer. This may push the tree to produce new growth, delaying its preparations for the cold season.
This is also the reason why even Japanese Maples grown in pots should live outdoors. Keeping your tree in the warmth of your house can prevent it from receiving the triggers for dormancy. This will stunt your Japanese Maple’s growth and drastically shorten its lifespan.
Spring: New Leaves Appear
Once the earth begins to thaw out in the springtime, new foliage will start to appear on your Japanese Maple. The buds on your tree’s twigs should begin to swell and burst open, revealing tender new leaves.
Many types of Japanese Maple sport intriguing foliage colors in the spring. Some notable examples include:
- Shin Deshojo: Bold crimson leaves in the early spring, which slowly fill in with a luminous green until they’re fully green by summer.
- Purple Ghost: Lavish purple-red foliage that goes green in the summer and then deepens to red with purple veins in the fall.
- Amber Ghost: Spring leaves have a dusty pink color with reticulated green veins, shifting to a toasted-marshmallow brown in summer.
- Katsura: Bold chartreuse leaves highlighted by bright pink edges,
In many places, Japanese Maples are among the first trees to leaf out in the spring. The buds should start swelling at the first hint of warm weather, and you’ll often see leaves emerging in mid-March. As always, the prevailing temperatures make a big difference. A particularly cold spring may mean your trees take more time. And some Japanese Maple varieties, like the brilliantly variegated “Geisha Gone Wild”, sprout leaves much later than others.
Summer: Full and Lush Foliage
From the middle of spring to the middle of summer, your Japanese Maple should experience its most vigorous growth. Many varieties turn deep green during this stretch, maximizing their chlorophyll content, though some remain red or orange until they drop their leaves in the fall.
Japanese Maples are much less likely to lose their leaves after the spring foliage is well-established. If your tree is shedding lots of leaves when the weather is still warm, it’s usually a warning sign. Let’s look at a few of the most likely reasons for a Japanese Maple losing its foliage early.
Dehydrated Japanese Maples Can Lose Leaves
A Japanese Maple that’s not receiving enough moisture may drop leaves in an attempt to conserve water. The main way that trees lose water is through transpiration, the evaporation of moisture through tiny pores in the leaves. Fewer leaves on the branches mean less surface area for moisture to escape.
This problem is most likely to happen during the spring or summer. Hot weather, bright sun, and rapid growth all increase the amount of water your Japanese Maple needs. These trees are also particularly thirsty during the first few years after they’re planted. It’s a good idea to check the soil every few days and water your Japanese Maple when the upper two inches are dry.
You’ll usually notice other signs of dehydration before the foliage begins to fall off. The leaves of an underwatered Japanese Maple tend to droop, curl, and turn brown and brittle at the edges. If you’re paying attention, you’ll often be able to refresh your tree with a thorough soak before it starts shedding leaves. Watering won’t remove the brown spots, but it should stop the wilting and prevent further damage.
Sun Scorch Can Damage Leaves
Another potential issue is overexposure to direct sunlight. Japanese Maples are understory trees by nature, meaning that they prefer to grow in the shade of taller trees. They like to receive lots of dappled sunlight, but too much direct sun can dehydrate and “burn” the leaves.
This problem often goes hand in hand with underwatering. A tree with a healthy amount of moisture is less susceptible to sun scorch. And younger Japanese Maples are at greater risk; as they get older, they tend to develop greater resistance to sun damage.
Sun scorch creates patches of dead tissue on the leaves, which can appear bleached and faded or dark and crispy. The damage will generally be worst on the side of the tree that gets the greatest sun exposure. Severely scorched leaves will die and fall to the ground.
If your Japanese Maple is in a pot, you can move it into a less sunny area. For a tree that’s rooted in the ground, some shade cloth can provide relief in hot weather. Adding more shade won’t heal the burned spots, but your Japanese Maple should replace them with healthy growth next season.
Overwatering a Japanese Maple May Cause Leaf Drop
Too much water is even worse for your Japanese Maple than too little. The roots will start to suffocate if the soil is too wet and sludgy. They may also develop potentially fatal fungal or bacterial infections known as root rot.
An overwatered Japanese Maple will display many of the same symptoms as a thirsty one. Wilting, yellowing foliage is a common symptom, though it’s usually soft and limp rather than dry and crunchy. The tree’s growth will usually grind to a halt, and if the problem persists, it will begin losing leaves.
For a Japanese Maple planted in the ground, the only real solution for overwatering is to stop watering. With a little luck, the tree will recover once the ground dries out a bit and becomes more aerated. Moving forward, you should remember to water only when the top two inches of soil feel dry.
If your Japanese Maple is growing in a pot, you may want to slide it out and check for rotting roots. Clip away any discolored or squishy root tissue, disinfecting your pruners before every cut. Then repot the plant in an all-new potting mix.
Overwatering is often caused as much by poorly-draining soil as improper watering habits. See this article for some tips on preparing a proper growing medium for your Japanese Maple.
Diseases and Pests Can Kill Japanese Maple Leaves
Leaf drop in Japanese Maples may also result from bacteria, fungi, and parasites. Here are a few of the most common plagues of Acer Palmatum trees:
Verticillium Wilt
This fungus can spread through contaminated soil, mulch, or pruning tools. Inside a tree, it chokes off the flow of moisture and nutrients, causing large clusters of leaves and branches to wither and die. Peeling back the wood may reveal dark streaks or rings, which is a strong indicator of verticillium wilt, though a conclusive diagnosis requires laboratory testing.
Unfortunately, there’s no cure, but a well-tended tree may be strong enough to fight off the infection. You’re better off trying to prevent the disease by being careful about where you get your garden supplies.
Anthracnose
Most common in damp springtime weather, anthracnose is another fungal infection that creates pits of wet, discolored rot in a tree’s leaves. Severe cases can make Japanese Maples lose their leaves in large clusters. Anthracnose is rarely fatal, but it’s not great for your tree’s appearance.
As with verticillium, chemical treatments are usually more trouble than they’re worth. Good sanitation practices are more effective, and you may be able to check the spread of the disease by pruning off infected branches.
Pseudomonas Tip Blight
This bacterial disease results from the bacterium Pseudomonas Syringae. It thrives in the same conditions as anthracnose and causes similar symptoms, including branch tip dieback and leaf spotting. You may also notice the veins in the leaves turning black. Advanced infections can make Japanese Maples lose their leaves in large quantities, though this is relatively rare in mature trees.
Many strains of Pseudomonas can resist pesticides, so your best bet is to keep your tree healthy and avoid contamination. Make sure not to overwater, especially when the weather is cool and damp, and try not to splash the leaves and bark.
Japanese Maple Scale
Despite the name, this insect can attack many different types of deciduous trees, but it’s a notorious pest of Japanese Maples in particular. Scale insects spend most of their lives anchored in place on the tree, underneath a waxy shell. Japanese Maple Scale is typically a dingy white color, and an infested branch may appear to be covered with grains of rice.
Japanese Maple Scale is hard to control once established. It’s important to monitor your tree to catch an infestation early. Pay special attention to the branch collars and cracks in the bark, which is where these bugs like to cluster. Look closely — they aren’t always easy to spot!
If you do see any Japanese Maple scale, horticultural oil is the most effective treatment. You’ll probably have to spray your tree at least twice, several weeks apart. Note that this product sometimes also makes Japanese Maples lose their leaves because it increases the risk of sun scorch. If possible, get some shade over your tree for at least the first few hours after spraying
Aphids
Aphids are common garden pests that can drain the juices from a Japanese Maple, stunting and shriveling its growth. In large quantities, the damage they cause may result in the tree losing leaves. Aphids come in a wide variety of colors, but on Acer trees, they’re usually green or yellow. They look like tiny, oval blobs clinging to the branches, particularly the newest growth.
It’s often possible to control an aphid infestation in the early stages by using a stiff spray of water to blast the bugs off. Make sure to get under the leaves as well as above them, since aphids often hide on the undersides. If the infestation persists, try treating your tree with insecticidal soap. As with horticultural oil, you’ll need to be careful about leaf scorch.
Late Frosts Can Kill Japanese Maple Leaves
If your Japanese Maple is losing its leaves in the springtime, it’s often due to a late-season cold snap. These trees tend to send out new foliage fairly early on, breaking their buds with the first flush of warm weather. This can leave them vulnerable if a frost hits later on.
You may be able to encourage your tree to be more patient by mulching with composted conifer bark. A three-to-four-inch layer should insulate the roots so that they don’t warm up quite as fast. Keep an eye on the weather report, too. If there’s a frost on the way and your Japanese Maple is already leafing out, you can try to shield it a bit.
Your best option is to wrap the foliage with breathable frost protection cloth. Bed sheets might also work if you’re in a hurry. Avoid clear plastic, which can act like a mini-greenhouse and might scorch your Japanese Maple’s leaves in the sun.
If you have a potted tree, you could also move it into an unheated but insulated indoor space such as a garage or shed. Just don’t forget to take them back outside as soon as temperatures return to normal. It’s best for your Japanese Maple to finish leafing out in the fresh air.
Why Is My Japanese Maple Not Leafing Out?
Japanese Maples lose their leaves naturally when the weather turns cold. But what if the foliage isn’t coming back as things warm up again?
First of all, take a look around the neighborhood before you get too worried. If lots of other trees besides your Japanese Maple are still leafless, you can generally breathe easy. The exact timing of bud break depends a lot on how long and cold the winter was.
If it’s just your tree that’s delayed, there are a few possibilities. Drought or verticillium wilt can sometimes kill off leaf buds before they open. Severe wind and frost can have similar effects. And your Japanese Maple may have suffered some twig dieback if it’s been through a particularly harsh winter.
Check for leaf buds on your Japanese Maple’s bare twigs. If there are none, or if they’re shriveled, dry, and crumbly, try bending the branch and scratching away a bit of the bark. Live wood should be springy and flexible, with a healthy green layer below the bark. Leave the living branches alone for now — there’s a chance they may still grow new buds.
On the other hand, a brittle, dry branch that’s all brown or beige underneath the bark is dead. Black streaks in the wood suggest that the culprit is verticillium wilt (see above). In either case, you’ll want to prune the dead wood from your Japanese Maple. Trim back to the nearest living buds without signs of verticillium. The branches you’ve cut back may not leaf out this year, but they should be able to recover and put out new growth next spring.
Other than selective pruning, all you can do is give your tree the right amount of water, fertilizer, and shade. With a bit of luck, it should bounce back.
Final Thoughts
There’s nothing to worry about when Japanese Maples lose their leaves in the autumn, but you should be concerned if it’s happening at other times of the year. Make sure that your tree is properly watered and sufficiently shaded during the scorching summer months, and shield it from spring frosts as needed. If your tree’s care needs are met, it should hardly ever have to deal with out-of-season leaf loss.