The fern is such a fascinating plant! One look at the staghorn fern and you realize how diverse nature can be. But with it, as with other plants, there can be some difficulties.
Overwatering, too much dry air, not enough moist soil, and pests are the main reasons for fern leaves curling. To fix curled leaves, water ferns only when the soil is 1 inch dry and provide at least 60-70% humidity. Also, monitor the health of the plant and take action if it shows signs of pests or disease.
Overwatering can cause fern leaves curling
It is a well-known fact that ferns like a humid environment. However, when growing this plant indoors, it is quite easy to overwater it and root rot may occur as a result.
A pot with no drainage holes can be another cause of root rot. This will cause the water to stagnate in the pot, and the roots will not be able to ‘breathe’ and will, therefore, begin to die. The rot can spread to the crown and stems of the plant.
If the roots do not supply water to the top, the leaves will start to curl and turn yellow. If the temperature is high and the humidity is low, the tips can turn brown and become crispy. You may also experience an unpleasant odor from the pot.
- Remove the fern from the pot and inspect the roots.
- If the roots are rotten wash them and cut off the damaged part.
- Wash the wounds with hydrogen peroxide. Dilute 1 part peroxide in 5 parts water.
- Plant the fern in well-drained, sterile soil.
- Only water the fern if the top one inch of soil dries out.
- Always use containers with drainage holes.
Too dry air
Air humidity plays a very important role in the life of the fern. These plants usually grow in the shade of the forest, where the humidity is very high, unlike indoors.
If the air in the room where the fern grows is dry, the fronds will begin to curl upwards from the tips. Leaflets will also curl, turn yellow or brown. This is how the plant reduces the amount of moisture it evaporates.
Causes of low indoor humidity are usually caused by heating during the colder months. But the plant can be damaged by being near other heat-radiating devices.
- Carefully remove the dry leaves.
- Place a stone tray half-filled with water near the fern. The water will evaporate and increase the humidity.
- Place all your houseplants close together. This way, the moisture will stay near the plants longer.
- Buy and install a humidifier. Keep the humidity near the fern at 60-70%.
- Avoid misting the leaves as this can lead to disease.
As I mentioned, the fern is a water- and moisture-loving plant. This means that it almost does not tolerate drought and underwatering. In dry, hot weather, the ground can dry out quite quickly. This is especially true for potted plants growing outside.
Some species of fern can go longer without water than others, but in general, it is not succulent and is not capable of storing large amounts of water.
If the soil in the pot is almost completely dry, the fern will start to lack water and the leaves will start to curl and shrivel up from the tips. Leaflets can fall off quite quickly, while fronds will stay alive a bit longer.
- Give the fern plenty of water to allow the excess to drain out.
- Water the fern when the potting soil is 1 to 2 inches dry.
- Install a soil moisture meter for better convenience.
- Keep a close eye on soil moisture, especially in the summer.
- Reduce watering over the winter, as the fern is dormant at this time and too frequent watering can lead to root rot.
Large trees provide the fern with not only high humidity but also enough shade. That is why the fern is a shade-loving plant and to successfully grow it we have to recreate its native conditions.
If a fern for some reason gets direct sun the leaves can get burned and curl up. The color of the burns can be either brown or black, depending on the intensity of the sun.
It is worth clarifying here that some fern species can tolerate more direct sun than others. The strong sun can damage even succulents, not to mention shade ferns.
Sun damage usually occurs in the summer when ferns are grown outside in direct sunlight. Or if the plant is placed too close to the glass of a south-facing window.
- Move the plant to a darker location. Most fern species can grow without direct sun at all.
- Heavily damaged leaflets can be removed because they will never come back to life again.
- Experimentally determine how much light your fern needs. Move it to a brighter or darker spot until you find the best spot.
- When buying a new plant, always accustom it to more light gradually.
The quality of the soil directly affects the appearance of the plant. If the soil retains moisture for a long time, the roots can start to rot. I already told you about this at the beginning of this article.
The next thing is the low nutrient content of the soil. The fact is that if the soil has too high a pH, nitrogen, iron, and other nutrients will not be available to the plant. As a result, chlorosis can occur. The symptoms of chlorosis are yellowing and curling of the leaves.
The problem can be solved with a holistic approach. First, you need to change the pH of the soil. Secondly, you need to fertilize the fern.
- If the soil is poorly drained, transplant the fern into more drained soil.
- Check the pH of the soil with tests available at garden stores.
- If the pH is above 7.0, make the soil more acidic by adding organic matter (compost). Another way to acidify is to use soil acidifiers, which are also commercially available.
- After that, apply a complex multipurpose fertilizer. Make sure it contains nitrogen, phosphorus, and potassium.
An over-abundance of nutrients can also hurt the health of the fern, as well as a deficiency. The fact is that if fertilizers are applied too often they will begin to accumulate in the soil in the form of salts. The salts are a harmful substance and can easily damage the roots.
If the roots are damaged by too much fertilizer, you get the same result as with root rot – the leaves will start to curl and turn yellow.
Although growing ferns in pots require a fair amount of fertilizer, you have to be modest about it.
- If you have fertilized your fern more than once a month, flush out the excess fertilizer with a stream of water. To do this, take the plant outside and water it for a few minutes. The running water will wash the minerals from the soil through the holes in the pot.
- Or transplant the fern into fresh, salt-free soil.
- Then fertilize the fern no more than once a month.
- Avoid fertilizing over the winter and in late fall.
Insects are one of the most important enemies of plants. If pests are not widespread, the plant may not even be seriously injured. But if there are many insects, the leaves will curl and turn yellow.
The most dangerous for ferns is scale. These insects stick to the stems and leaves and feed on the sap of the plant. This pest looks like white lumps all around.
The fern can also be infested by mealybugs or other insects. So you need to inspect the leaves from time to time and act proactively.
- Inspect all parts of the plant thoroughly.
- If you notice insects, remove them with your hands.
- Next, dilute 2 teaspoons of dish soap in half a gallon of water and add 2 tablespoons of horticultural oil. Stir the mix well and spray the fern.
- If the insects are not gone, spray again.
- If the pest spread is significant and horticultural oil fails, spray the fern with a systemic insecticide.
In nature, plants have stronger immunity than indoor plants. In addition, wind and other weather conditions make it difficult for diseases to develop quickly. All this leads to the fact that ferns rarely get sick in nature, which cannot be said about indoor cultivation.
Indoors, it is usually not as well ventilated and the conditions are more suitable for disease development. A fern, like other plants, can become ill with fungal or bacterial disease. The symptoms of most diseases are curling and browning of the leaves. There may also be spots or mildew on the leaves.
- Remove the most damaged leaves.
- Make sure the room where the fern is growing is well ventilated.
- Spray the plant with a copper-containing fungicide. If it does not go away, spray the leaves several times with different fungicides, varying them.
- Do not overwater ferns as rotten roots also cause leaf disease.
The last possible cause of curling leaves of ferns is transplant shock. In fact, transplanting is a real challenge for all plants. No matter how careful the transplanting is, the roots will be disturbed and this will definitely affect the appearance of the plant.
Even the simple act of moving a plant from one place to another can cause stress. But I have to say here that not all plants go through a transplant shock; for some, it goes very smoothly.
The timing of the transplanting is also important. If you transplant a fern in the heat of summer, this is an additional stress factor. Increased watering will not make it easier.
- If the leaves curl after replanting, move the fern to full shade. The deeper the shade the better.
- Water the plant in moderation but do not let the soil dry out more than 2 inches.
- When you see the plant produce young shoots, slowly accustom it to more light.