Maples are such wonderful plants that you wish there were as many of them as possible. Personally, I like the Japanese maples best because of their compact size and split leaves. However, you may have some problems when you decide to grow these trees.
Environmental causes such as too much sun or temperature stress can be a reason for Japanese Maple leaves to curl. Diseases, pests, and improper watering can also cause the leaves to be curled or deformed.
Below you will learn about each case in detail. In addition, you will get recommendations on what to do to fix it.
| What causes Japanese maple leaves to curl? | Symptoms | How to fix |
| Underwatering | Maple leaves curl inward and burn along the edge. | Water the maple with plenty of water. |
| Diseases | Maple leaves have black or brown spots and curl up. | Ensure good air circulation around the maple. Spray the tree with fungicide. |
| Temperature stress | The leaves curl inward and partially turn purple. | Water the maple with liquid fertilizer and shade it for a few weeks. |
| Too much sun | The curling begins at the tips. Leaves are burnt along the edge. | If possible, shade the maple for a while. Water the maple with additional water. |
| Overwatering | Yellowing and curling of leaves. | Water the maple only when the soil is two inches dry. Transplant the maple to a less wet location. |
| Improper fertilization | The leaves are soft and slightly curled. | Fertilize the maple no more than once a year. Acidify the soil around the tree. |
| Pests | Leaves curl outward (down). There are traces of insects on the leaves. | Spray maple with horticultural oil or acaricide. |
| Transplanting | Leaves are deformed and drooping. | Keep the maples shady and water on time. |
Underwatering
As I mentioned before, the first cause of curled leaves is underwatering. This can happen most often in sunny and hot weather. Another factor that aggravates the situation is the hot wind.
As a result, the leaves will curl inward and maybe be burnt at the edge. If you notice this problem in time, it can still be fixed.
You need to water the maple with plenty of water, the soil around it should soak in. The next watering should be no sooner than the soil dries 1-2 inches deep.
Twisting from lack of water often occurs with newly planted maples. Trees that already have a heavy root system rarely suffer in this way.
Curling is also very common if you grow maple trees in a pot. The potting soil dries out very quickly in hot weather. So you need to keep a close eye on the moisture of potting soil or transplant the maple into the garden.
Read more: How often to water a Japanese maple?
Diseases
Diseases can also cause curled maple leaves. Here, anthracnose should be mentioned first. This disease is caused by a variety of pathogens and can be quite a serious threat to young maples.
In the early stages of the disease, dark spots appear on the leaves and the leaves curl. If nothing is done, the disease will affect the young branches and the leaves will shrivel and fall off. This disease rarely kills maples, but young trees can be severely affected.
To solve the problem, you need to make sure that the maple gets enough light. Also, make sure that the air moves freely around the tree. If necessary, transplant it to a more open area.
The next thing you should do is to spray the maple with a suitable fungicide that is easy to find on the market. Repeat the spraying after a while. In some cases, you may have to spray several times a season.
Also, don’t over-water the maples and if you have automatic watering, don’t direct the sprinklers at the leaves.
Read more: Japanese Maple Diseases With Pictures
Temperature stress
Sometimes it happens that the air temperature is very high during the day, and at night it gets suddenly cold (but not frosty). As a result, the leaves may curl up to protect themselves from the cold. Also, some of the leaves may change their color to red or purple.
Usually, this sudden temperature change can occur in late spring or early summer. Young maples or maples that are growing in pots are the most susceptible.
The maples will not get serious damage, but the twisted leaves can sometimes stay that way for the whole season.
You basically don’t have to do anything; the tree will recover after a while and everything will be fine. But if you want to help your maple, first of all, water it well. Next, dilute multipurpose liquid fertilizer in a bucket and water the maple. One watering with liquid fertilizer is enough.
You can also shade the maple with a garden umbrella for a few weeks. This will reduce exposure to the sun and make it easier to recover from temperature stress.
Overwatering
Too much watering or heavy rains can cause maple leaves to curl. Some maples (e.g. silver maple) can withstand prolonged waterlogging. At the same time, Japanese maple does not tolerate overwatering at all.
As a result of too much water, the roots start to lack oxygen and root rot begins. What you will notice is the yellowing and curling of the maple leaves.
The first thing you need to do is to stop watering. Next, water the maple only when the soil is 2 inches dry. If you notice the problem at an early stage and stop watering frequently, the tree will soon recover.
If the soil around the maple is wet all the time, whether you water it or not, you need to transplant it to a drier location (if possible, of course). When replanting, use well-drained soil. Put stones in the bottom of the planting hole as drainage.
Excessive sunlight
The next problem is too much sun. In early spring, when the young leaves begin to unfold, the weather can be cloudy for a long time. Suddenly sunny weather and heat come in. Leaves that are used to growing without the bright and direct sun curl inward to avoid damage from the sun’s rays.
Other symptoms can be browning of the leaf edges or brown spots in the center of the leaf. It is also common for the curling to start at the leaf tips.
Typically, twisting from the strong sun occurs in hotter climates.
The obvious solution to this situation is to shade the maple from the excess sun for a while. But don’t shade it completely, early sun is still necessary for the maple. When the curling stops, the shade can be removed.
If the maple is already big, you can hardly shade it. In this case, the only thing you can do is to water the maple additionally, but don’t overwater it. Even if the tree gets damaged, it will recover after a while.
Read more: Can Japanese maple grow in full sun?
Improper fertilization
If you are into mineral fertilizers and have fed your maple a lot, the leaves may curl and droop.
This is primarily due to an excess of nitrogen. In this case, the plant will grow vigorously but the leaves and branches will not mature properly. As a result, the leaves will be soft and twisted.
There is nothing you can do to correct this situation. In the future, avoid feeding maple trees heavily.
The second case is when the soil does not contain enough elements or is not available to the maple. I am talking about magnesium now. This element is essential for photosynthesis. Usually, the soil has enough of it, but if the soil is very alkaline it will not be available.
If your maple leaves curl and turn yellow, but you can still see the green veins, it is probably chlorosis. You need to acidify the soil, which can be done with acidifiers available at garden supply stores.
Also, fertilize the maples no more than once a year with a slow-release multipurpose fertilizer. This is best done at the beginning of the season.
Read more: What kind of fertilizer does a Japanese maple need?
Pest infestation
Another cause of maple leaf curl can be pests. If the distribution is not great, you may not even notice them, but if there are a lot of them, the maple can be severely affected. This is especially dangerous for young trees.
The first type of pest is an insect that succumbs to the branches and leaves of the tree. One of the most common insect pests is aphids. It attaches itself to the lower parts of the leaves and sucks the sap out of them. To get rid of aphids, you need to spray your maple tree with horticultural oil or another insecticide. These products are usually very effective and the aphids will disappear after one spraying.
The second type is spider mites. These are small red or red-brown bugs that weave cobwebs on the leaves and branches of maple trees. They stick to the tree and cause the leaves to curl. To get rid of them, you need to use a special product called acaricide.
Japanese maple leaves curling after transplant
The final cause of leaf curl is transplant shock. After planting in a new location, the maple begins to stress due to the sudden change in growing conditions and, as a result, the leaves become deformed and fall off. Dwarf Japanese maples are particularly prone to this.
To avoid transplanting shock, you should plant maples in early spring before they begin to grow. Also, don’t damage the roots when transplanting.
If transplant shock occurs, shade the maple if possible. Water the maple in time and don’t let the soil dry out.
Read more: How To Reduce Japanese Maple Transplant Shock?
Herbicide damage
Very often when you treat your lawn with weed killer, drops can get on the leaves of Japanese Maple. This is especially true for dwarf or weeping varieties.
As a result, the leaves may curl and turn brown. The leaves will then shrivel up and fall off.
Even if you didn’t treat your lawn, your neighbors may have done so. A gust of wind may have brought a small amount of herbicide and your maple was affected.
The only thing to do in this case is to wash the herbicide residue off the leaves and water the maple with liquid fertilizer. If the damage was minor, the tree will soon recover.