Growing peppers truly is a science. It can be accomplished with simple means; soil, water, and the sun. Or, it can be done in a complex greenhouse with precise nutrients and watering. However, as with anything that is alive, bad conditions and nutrient imbalances can lead to stress and other issues.
With peppers, the plant will give clear signals when something is wrong. One common issue that is found in pepper plants are when the leaves begin curling. It can happen for several reasons, and in this article I will discuss what you can do when your pepper leaves are curling.
Why Are My Pepper Leaves Curling?
Of the many potential causes, there are 5 that are most likely to be causing pepper leaf curl. Each has a slightly different presentation of the problem, so try to diagnose your issue and treat accordingly.
Leaves curling is a sign of stress in your plant, and it can usually be remedied with some simple adjustment to your plant care routine. Whether you’re growing in containers or in the ground, leaf curl is a possibility.
One of the worst things you can do to your pepper plants is to keep the soil too moist. Pepper plants prefer soil that is evenly moist, while too much water will lead to many problems.
Overwatering can cause pepper leaves to curl due to the roots’ inability to access enough oxygen and nutrition from the soil. Overwatering will also usually cause yellowing leaves and stunted plant growth.
The most common reason pepper plants become overwatered is poor drainage. In pots, make sure to remove the bottom saucer to allow excess water to flow out of the drainage holes.
The solution: Water only when the soil is adequately dry. You can know that the soil is dry enough to water by feeling the soil 1-2″ below the surface, or by lifting the pot to feel the plant’s weight.
If you allow the plant to dry too much, the leaves will begin to wilt, but will quickly rebound after being watered. You can also try using a cheap water meter from amazon to check soil moisture levels.
Plant edema is a common cellular disorder caused by irregular water retention. It will appear in peppers as a whitish, crystallized texture underneath the leaves. Extreme edema can cause plant leaves to curl.
Edema is most common on indoor pepper plants, but can occur in any conditions. It is not a very well understood disorder, but in our experience, a few environmental changes can help.
The solution: Improve aeration for indoor plants by using a small fan to move the air around your plants. Also, if it the air is very dry, increase humidity or spritz plants with water in the early morning each day.
Different pepper varieties are more vulnerable to plant edema. One plant may have a severe case, while a different variety right next to it is unaffected. It is not spreadable like a disease.
One possible cause for ‘bubbled’ curling is a nutrient deficiency. Calcium is a secondary nutrient for pepper plant growth. Among other things, it is used by plants to develop strong cell walls.
When plants lack calcium, leaves can not develop properly and will begin to appear curled and/or bubbly. This is sometimes accompanied by brown spots on the leaves and there may be other signs of nutrient deficiency like yellow leaves.
The solution: Test soil for pH and calcium. Soil acidity affects a plant’s ability to take up and use all the available nutrients.
Note: Calcium is rarely deficient in soil, it is more often that plants are unable to access it (nutrient lockout). Testing for pH annually will help you improve your soil and enable your pepper plants to take up all the available nutrients.
If your soil does lack calcium, it is available to add to soil in many formats (cal-mag sprays, etc.) Be sure to add calcium and magnesium, as adding just one nutrient can cause a deficiency in the other. These nutrients are sometimes, but not always included in all-purpose fertilizers, so check the ingredients!
Miracle-Gro Organics is a simple, well-balanced fertilizer that contains calcium and magnesium.
Many potting mixes will also include calcium, but not all. Check your soil to see what nutrients are added. If you are planting in the ground, try sending a soil sample for analysis.
Too Much Light
Providing light to your pepper plants is essential. Most pepper varieties like full sunlight throughout the season, so if you are planting outdoors, lighting is unlikely the issue.
A more common issue is caused by using indoor grow lights incorrectly. Grow lights can vary widely in brightness and intensity. They are essential if you start your own pepper seeds indoors, but you have to follow the specific light instructions for how close the lights should be to your plants.
If your plants are too close to the light, you will begin to see the leaves curling up and closing in rebellion from the intense light. This problem can eventually cause pepper leaves to dry up and fall off, often turning brown and crumbling when squeezed.
Keep in mind, this issue usually affects young, tender plants more than mature peppers. Seedlings are more delicate than fully-formed plants.
The solution: If you think your plants have light burn, adjust your lights a few inches higher. Our grow light needs to be 12-18 inches away from the canopy of leaves.
Also, make sure the lights are set on a timer to be on for 12-16 hours, and off for the rest of the day. Check that the timer is working properly, as 24/7 light is not good!
If your outdoor plants have leaf curl, the issue is not likely to be lighting. One possible cause is improper hardening off. When indoor plants move outside, they must be gradually adjusted to the direct sunlight. Sudden exposure can lead to curling and sun scald.
Unchecked insect infestations can quickly become the bane of your garden. They come from seemingly nowhere and can wreak havoc on your plants in a matter of days.
Curling pepper leaves can be a sign of a pest problem, though it will typically be focused on individual leaves rather than the whole plant. Curled and bubbled leaves could be the leaves that the insects have been feeding on.
Unfortunately, pest removal is more difficult than preventative care. However, you can take some measures to try to alleviate the issue and get rid of most of the insects.
The solution: Spray off aphids and other sap sucking insects with water. Spray with a diluted neem oil solution for extra protection. Also, plant alyssum and other beneficial companion plants to attract predatory insects that eat common pests.
As a preventative measure, neem oil is effective – simply work the suggested amount into your soil before transplanting or spray a diluted solution onto the foliage.
Other Causes Of Pepper Leaves Curling
Though the causes mentioned above are the most common, there are many other potential issues that can cause curling leaves. If you are sure that none of the other causes apply, or you have tried without success, there are some other, less common causes.
Your plants could be root bound. Learn more about root bound plants in our article here. This issue is caused by plants being kept in containers that are too small. The roots can become entangled, sometimes causing distorted leaves.
Your pepper plants could have a bacterial infection, though this is often accompanied by brown, circular spots. This is often caused by using sterilized soil which can attract new colonizers, or by soil splashing on low leaves. Read more about pepper plant diseases here.
If you are growing indoors, your plants may suffer from poor pollination, which can cause distorted leaves. Try hand pollinating or shaking the plants after the flowers have opened. This issue is also accompanied by dropped flowers and a lack of pepper pods.
After treatment for curled pepper leaves, do not expect the leaves to flatten out and look perfectly healthy. Just because the plant doesn’t re-form to look beautiful doesn’t mean the issue hasn’t been resolved.
Expect new leaves to look properly formed and understand that the curling leaves will remain curled. The best way to solve most planting issues is to learn from past mistakes and avoid them in the future!
Learn more about growing peppers here to give your pepper plants the best chance they have from day 1.
Remember, curling pepper plant leaves are usually nothing to worry too much about! Look at your plants as a whole and try not to get too hung up on just a few curled leaves. If the newest foliage looks healthy, then be happy about that. Keep an eye out for more concerning issues like fungal issues and garden pests.
I hope this article helped you diagnose why your pepper plant leaves are curling. Growing peppers can be a challenge, but the reward is always worth the extra effort. Good luck, and let us know if you’ve had success with treating your curling pepper plant leaves!