5 reasons why your plant curls its leaves

In a plant, curling leaves are a cry for help, an SOS, a message in a bottle. It's a sign that something is wrong and that the plant may die. So you'll need to act fast. But before you do anything, you must identify the problem causing the leaves to curl. Whether it's watering, light, temperature, or fertilization, we'll explain the possible causes and how to fix them.

Your plant is curling its leaves because it's lacking water

To revive your plant, water the substrate, not the leaves – Photo by Tuchkovo

When your Pothos or Calathea picturata curls its leaves, it limits the surface area exposed to the sun. This helps it reduce evaporation and water loss.

Most often, your plant curls its leaves when it's lacking water. This happens if you've forgotten to water it for a long time, if your watering schedule is irregular, or if you aren't watering it enough. To be sure, feel the substrate. Is it dry on the surface and deep down? Grab your watering can. You can also check the substrate: if there's a gap between the pot and the substrate, it means the substrate is completely dry.

You should then water thoroughly, until water flows out through the drainage holes. However, if the soil is too dry, it can no longer absorb water. You'll notice this within the first few seconds: the water will run off as soon as you pour it, without penetrating the potting mix. In this case, it's best to perform capillary watering: fill a container with room-temperature water and place your plant's pot inside it. Let it soak for at least 15 minutes to rehydrate the substrate and the plant.

Plants can also become dehydrated due to overwatering! When a plant is overwatered, its roots rot. They can no longer absorb water and nourish the stems and leaves. And the leaves curl up to reduce water evaporation.

Check the substrate to see if your plant is suffering from excess water. Even water-loving species, such as papyrus or alocasia zebrina, need their substrate to be moist, not waterlogged. If the soil is muddy, you've overwatered it. Another symptom to confirm the diagnosis is the condition of the roots. Healthy roots are firm and light in color. When rotten, they turn brown, become soft, and smell bad.

Don't worry! It's not necessarily too late to turn things around. Start by removing the plant from its pot and discarding the old substrate. Take this opportunity to trim away the rotten roots using clean, sharp pruning shears. Then replant it in a pot with drainage holes, using fresh, well-draining substrate suitable for your plant. Not sure which one to choose? Download the Monstera app. We'll recommend the right type of substrate for each variety.

The leaves of your plant are curled up due to a pest infestation

Aphids aren't exactly known for being discreet – Photo by Mohammad Marafi /iNaturalist

In houseplants as well as in tomatoes, the lemon tree, and other garden-grown varieties, curled leaves can be the result of a pest infestation. “Biting-sucking” insects, such as whiteflies, aphids, and scale insects, bite into the foliage and stems to suck out the sap. This directly causes the leaves to wither and curl up on themselves.

Examine the leaves to determine if your plant is affected by pests or disease. Look for signs of puncture marks, rot, and honeydew (a sticky film). You may also find insects, larvae, and whitish clusters.

Is your plant overrun with pests? Isolate it from the rest of your collection and cut off the most severely affected parts. Most of the time, a shower with lukewarm water and cleaning the leaves with liquid soap are enough to get rid of the pests. However, if you're dealing with mealybugs or a severe infestation, you'll need to use insecticides and pheromone traps.

Pests and diseases thrive when growing conditions are poor. They're particularly common when humidity levels are unsuitable. To prevent your indoor jungle from being attacked, establish a proper care routine. Water regularly, but not excessively; air out the plants; and make sure they get enough light. Finally, inspect the leaves of any new plants you bring home. Pests are sometimes sold along with the plant! If in doubt, quarantine the new arrival until you're sure it poses no threat to the rest of your collection.

Leaf curling is caused by improper temperature

Misting helps cool your plants down a bit during heat waves. Photo by Irina Zharkova

Curling its leaves helps the plant protect itself from cold and heat. The varieties we grow indoors often originate from tropical or desert regions around the world. They generally thrive at temperatures between 15 and 25°.

If your plant curls its leaves in winter, it's likely because it's cold and you're not providing enough heat. Move it to a room where the thermometer reads at least 18°. Plants also suffer during heat waves. To protect them from extreme heat, keep them away from windows, perform regular misting, and increase the frequency of watering.

Is the temperature ideal, yet your plant isn't unfurling its leaves? It may be sitting in a draft. Once again, the solution is simple: move the pot to a different spot!

Curled leaves are caused by a lack of light

Indoors, our plants often lack light

Are the leaves of your Stromanthe sanguinea curling up and pointing downward? The plant is likely trying to protect itself from excessive light.

This tends to happen in the summer, when you take your plant outside to the garden so it can enjoy the fresh air. Unaccustomed to these new growing conditions, your plant will curl its leaves to limit its exposure to the sun. Move the pot to a shady spot and gradually acclimate your plant to outdoor conditions. Start by taking it outside for a few hours, either in the morning or evening. Gradually increase the duration and intensity of its exposure. Even after a few weeks, always be careful to stick to the recommended exposure to avoid burning the leaves. Some varieties prefer partial shade, while others thrive in bright light. But only succulents and cacti can tolerate direct sunlight.

It's rare for our houseplants to get too much light indoors, unless you live in a very sunny region and place a shade-loving species (such as Marantaceae or aglaonema costatum) behind a window that lets in too much light. For these plants, choose windows facing east or west. Do you live in Nice and have a south-facing window? Move the pots back one meter from the window or hang a sheer curtain to protect your plants during the hottest hours of the day.

In our homes, plants are more likely to suffer from a lack of sunlight than from too much of it. A plant that lacks light doesn't curl its leaves; instead, it tends to turn them toward the sun.

What if it's the fertilizer?

Repotting provides new nutrients – Photo by Satura / Envato

Finally, leaf curling can be caused by a nutrient deficiency. Again, there are two possibilities.

The most common? Your Ficus elastica 'Tineke' has been in the same pot since you bought it; you've never repotted it or fertilized it (or perhaps both). The soil is depleted; it no longer contains any nutrients, and your plant is starving. Curling leaves aren't the only symptom. Growth slows down; your plant stops growing and doesn't produce new leaves.

To fix this, give your plant some fresh potting soil! Repot it into a larger pot. If it's too large to move, top-dress it instead. Use a garden fork to remove one-third of the soil and replace it with a suitable substrate.

For overzealous gardeners, leaves may curl up due to an excess of fertilizer. Over-fertilization occurs when you haven't followed the frequency or dosage recommended by the manufacturer. Other signs indicate that your plant has been over-fertilized. For example, brown spots may appear on the foliage.

There are two ways to remedy this problem. The first is to leach the soil, which means watering very thoroughly to flush some of the nutrients out of the soil. You can do this indoors, in your shower. But it's best to let your plants stand under a summer downpour so they can benefit from the rainwater.

You can also choose to repot. Even during the growing season, you'll need to wait at least four weeks after repotting before fertilizing again. This is because the new substrate is perfectly balanced and provides your plant with exactly what it needs, without excess. There's no need to add more! The roots wouldn't be able to keep up, and you'd risk damaging the leaves.

Want to avoid making the same mistakes? Check out our tips in our article on How to fertilize indoor plants?

Frequently Asked Questions About Plants and Curling Leaves

Why are my plant's leaves curling?

Leaves curl when the plant is under stress: lack of water or nutrients, unsuitable temperature, excessive light, or pest infestation. Curling is a defense mechanism: the plant reduces its exposed surface area to limit evaporation and damage.

How do you treat leaf curling in a plant?

The treatment varies depending on the cause of the curling. If the leaves are curling because your plant lacks water, water it more frequently and in greater quantities. Leaves may also curl due to excessive light (in which case you should move the pot away from the window), an unsuitable temperature, or a pest infestation, which you'll need to treat.

Why are the leaves on my Monstera curling?

Your Monstera's leaves may curl due to a lack of water, a pest infestation (thrips, scale insects, whiteflies, etc.), too much light, or a nutrient deficiency. Depending on the problem, adjust your watering schedule, move your plant, treat the infestation, or apply fertilizer.