There are several different factors that can cause the leaves on a pepper plant to curl, but all of them are harmful to the plant’s production capabilities and need to be rectified in a timely manner. The leaf curl may present upwards or downwards depending on the environmental cause.
This article provides the basis for understanding the problems, symptoms, and treatments of pepper plant leaf curling.
6 Causes of Pepper Plant Leaves Curling
Pepper plant leaf curling is an important first sign that there is a problem with your pepper plants. The most common environmental factors that can cause a pepper plant’s leaves to curl include inadequate watering, insufficient light, nutrient deficiencies, pests, and leaf curl diseases.
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1. Overwatering
Implementing a proper watering schedule is very important for your moisture-sensitive pepper plants. Ideally, you should water your pepper plants during the morning or evening hours. This ensures that any water left on the leaves isn’t there during the hottest part of the day, which can lead to severe leaf damage. Proper watering can easily be achieved by using ground watering techniques like a soaker hose.
Overwatering your pepper plants is a big mistake but unfortunately, it is very easy to do. Saturated soils will quickly deplete oxygen, and pepper plants are very intolerant to those conditions. The extreme stress from remaining in these conditions will quickly cause the pepper plant’s leaves to wilt, curl, and die.
2. Poor Soil Drainage
Pepper plant leaf curling can be caused by an excess of water in the soil. This can be caused by overwatering, but it can also be caused by soil with poor drainage capabilities. Soil with a high clay content will not drain as easily as soil with a higher sand content. The best soil for growing peppers consists of a well-draining loam or sandy loam that is rich in organic matter and has a pH that is ideally between 6.7 and 7.3
3. Light Imbalance
Pepper plants originate from tropical regions, so they have evolved to tolerate a tremendous amount of sun and heat. With those adaptations, pepper plants have lost the ability to tolerate cool, low-light growing conditions. If pepper plants are not receiving enough sunlight, then they may begin to experience leaf curling and poor fruit production.
On the flip side, if pepper plants are being grown indoors under grow lights, you may see the leaves curling inwards in an attempt to restrict light exposure. Too much intense light will lead to leaves curling and eventually falling off the plant.
4. Nutrient Deficiencies
Nutrient deficiencies are the lack of available nutrients in the soil. All plants require 14 different mineral components to complete their metabolic activities related to growth and reproduction. When nutrients, such as nitrogen and calcium, are in short supply it can cause issues such as stunted growth, poor fruit production, and curling of foliage.
Lack of Calcium
Calcium deficiencies are common in pepper plants. The beginning symptoms of calcium deficiency include overall stunted growth, and then yellowing and curling of leaves. If the deficiency continues it could create rotting flesh in ripening peppers. Calcium deficiencies can ruin entire crops of peppers but are easily prevented by maintaining an adequate fertilizer schedule. Calcium becomes less bioavailable during times of drought.
Lack of Nitrogen
One of the most commonly lacking macronutrients, nitrogen will cause the plant’s leaves to yellow, brown, and curl. Generally occurring on lower, older leaver first, and during fruiting periods when nitrogen is most needed. Applying a soil fertilizer that is focused on fruiting is important in keeping your pepper plants productive during their short production season.
5. Nutrient Toxicity
It is important to note that although less likely, nutrient toxicity can occur and present symptoms very similar to those of nutrient deficiencies, including pepper plant leaves curling, discoloring, or dying. A handheld soil nutrient level meter is the simplest way to determine the exact level of nutrients available.
6. Pests and Diseases
Pepper plants can be a host to many pests and diseases, including bugs, bacteria, and leaf curl viruses. Be particularly watchful during the seedling stage as this is when the pepper plants are less likely to recover after a major attack.
Integrated Pest Management (IPM) is a scientifically proven way to control these unwanted insects without using excessive insecticides. It includes removing invasive plant species, planting native species, creating shelter to attract predatory insects and birds, and companion planting techniques.
Insects
Aphids and white flies are attracted to pepper plants and cause leaf curls when they suck moisture from the leaves. Although the insects might be hard to find, all cases will include evidence of actual leaf damage from the infestation along with the presence of curling and yellowing leaves.
Pepper Yellow Leaf Curl Virus (PYLCV)
There are several pepper plant viruses that specifically infect the leaves of pepper plants, causing them to severely curl. The timely discovery of these infections is important because if left to spread, they will infect and destroy the entire field of peppers.
Leaf curl viruses from the Polerovirus genus include symptoms of upwards rolled leaf edges and yellowing of leaf veins. These cases are usually fatal to the plant and all infected plants should be removed.
How to Treat Leaf Curl on Pepper Plants
Treatments of pepper plant leaf curling depend on the factor causing the issue. The following describes the techniques commonly used to treat or prevent leaf curling in pepper plants.
Reduce Watering Frequency
Pepper plants require consistent soil moisture but don’t do well in saturated soils. Test the soil moisture level by sticking your finger at least 2 inches deep into the soil near the plant. If the soil feels dry to the touch, then it needs watering. If the soil feels moist, then there is no need to water.
Being from an arid region, pepper plants might not need to be watered every day and slight leaf curling might be due to heat instead of moisture needs, so make sure to check your soil before watering first.
Ensure Soil is Well Draining
Soil saturation near your pepper plants can be prevented by mounding the soil around the plant to direct standing water away from the stem and roots. Using well-draining soil like a sandy loam is ideal for pepper plants. Try to avoid large dry spots or standing water in the soil of the garden area.
Position & Light Requirements
Starting your pepper plants off in the right location is very important for the general health of the plant and its ability to produce a bountiful crop. Pepper plants require consistent daytime temperatures above 65 degrees Fahrenheit to produce peppers, which is why it is important to plant your peppers in full sun, especially in regions with colder climates.
Too much light intensity can cause pepper plants to curl inwards, as the plant attempts to reduce the light intensity. In this situation consider relocating the plant if it is in a pot, or provide some netting or another form of dappled shade to filter the light.
Hardening off Before Planting Outdoors
Hardening your pepper plants is very important because it strengthens the plant while protecting them from the shock of early spring’s cold night air. A few weeks after your area’s last frost and a week before you want to transplant the pepper plants into the ground, you should begin to harden your plants.
Harden your pepper plants by bringing the seedlings outside in warm and sunny weather for a few hours each day, increasing the amount of time gradually over the next week until you are confident that they are strong enough to withstand transplanting. Always bring your pepper seedling back inside at night during this hardening period.
When & How to Fertilize Peppers
Nutrient deficiencies can be caused by soil lacking in organic matter or from leaching due to over-watering. Implementing a fertilizing schedule will help maintain the health and well-being of your pepper plants. Studies from the Journal of Applied Science have shown that applying consistent fertilizer treatments, especially for phosphorus, calcium, and potassium, has a significant impact on the overall growth of the plant, the yield of the peppers, and their ability to withstand cold temperatures.
Using an all-in-one slow-releasing fertilizer formula specialized for pepper at the beginning of the growing season will ensure your peppers have the nutrients that they need when they require them. During the seedling and vegetative periods, nitrogen is in greater need. While calcium, phosphorus, and potassium are more likely to be lacking during the fruiting stages.
Bonemeal
At the point that your pepper plants have reached about 8 inches tall, you may want to apply a bonemeal fertilizer, which is a great source of nitrogen, calcium, potassium, and phosphorus. Bonemeal fertilizers can increase available nutrient levels in the soil and raise soil acidity to a pepper-preferred pH. Bonemeal is typically slow-releasing, so add it to the soil in the spring, and your plants should benefit from the feedings late into the fall.
