Sunscald on Peppers – Causes and How to Prevent It

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Growing peppers comes with many potential issues throughout the season. One common problem for growers is sunscald on peppers. Yes, the sun is a vital component of growing peppers outdoors, but it can also be too intense for tender plants and fruits.

In this article, I will show you how to identify sunscald on pepper plants and how to avoid it in the future. There are several growing techniques to help you prevent sunburn on your peppers.

In this article:

• What is sunscald?
• Signs of sunscald
• Avoiding sunscald

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What is Sunscald?

Sunscald on plants is defined as damage to plant tissue from excessive sunlight exposure. This may seem strange when you consider that plants need sunlight to produce energy and grow.

Sunscald (or sun scald) on peppers is usually caused by excessive sunlight to tender portions of the plant. These include younger leaves and especially the developing fruits. The less-developed skin of young fruits cannot tolerate full-sun conditions on many pepper varieties.

This exposure will essentially cause an injury to your peppers, almost like a sunburn for your plants. It is especially common when plants are transitioned from an indoor to an outdoor growing space with fruits already on the plant.

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How to Identify Sunscald on Peppers

There are two main types of sunscald on peppers: on the leaves or on the fruits. Damage to leaves is less serious, as the plant typically recovers and grows new leaves to replace the damaged ones. Sunscald on fruits, however, often makes those peppers unusable.

Sunscald on Pepper Fruits

Sunscald on peppers can be mistaken for other conditions, but it has a few defining characteristics. It will often start as a white or black discoloration on a pepper’s skin or on the leaves.

These spots on the fruits are caused by direct sun exposure, and will worsen over time and turn soft. Once the tissue is damaged, it is much more susceptible to diseases and plant pathogens. This often leads to moldy or rotting fruits.

Many pepper varieties hang down naturally and are thus shaded by the foliage of the plant. However, if the peppers grow upwards or are otherwise exposed to prolonged sunlight, then sunscald becomes an issue.

This can also happen in the late afternoon when the sun is lower in the sky. The angle of the sun may hit some of the peppers around the outsides of the plant, often burning them.

Some light purple streaking is normal, so don’t be worried if you see a bit of purpling. As long as the peppers remain firm and do not show signs of mold. I often see this on banana peppers that get a bit of sun exposure during the day, but they rarely turn white or become soft.

Brown or white foliage

Fruits are not the only part of a pepper plant that is vulnerable to sun scald. Without proper hardening off, tender young pepper plant leaves may become damaged from excessive sunlight.

Sunscald on pepper leaves will start with leaves turning brown or ivory-white, quickly becoming dry and crispy to the touch. Though sunscald on plants may seem counter-intuitive, it is a real concern if you are growing in full sunlight. Make sure to transition your young pepper seedlings gradually to let them adjust to the sun.

Alternaria Fruit Rot

Alternaria fruit rot is a condition that is mainly caused by physical injury to your peppers. Lesions form at the site of the injury and eventually sink. They will often become covered in a brown or black fungus. Fruit rot can also be caused by sun scald, or by extreme cold, heat, insect damage, or a calcium deficiency.

See more on fruit rot here.

If these spots don’t look like your problem, see other causes of spots on pepper leaves here.

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How to Prevent Sun Scald on Peppers

The best way to fix sunscald is to avoid it altogether. Once it occurs, the affected leaves and fruits are essentially dead. If you plan to sell your peppers, sunscald may cause a loss of some of your crop. Follow these tips to help reduce your risk of sunscald on peppers.

Harden off plants

When starting pepper plants from seed, it is often required to start indoors during the winter. Indoor conditions are very different from outdoor conditions. The sunlight emits different types of radiation from grow lights, and wind and rain will stress the plants as well.

Learn more about hardening off pepper plants here.

Give your plants a proper transition period when moving them outdoors. If you simply put your young pepper plants outside in full-sun, they will definitely have issues, starting with wilting leaves, and quickly leading to sunscald.

I usually give our plants at least 1-2 weeks to slowly adjust to the outdoors. This means gradually increasing the time spent outside each day until they are ‘hardened off.’

Fertilize during early plant growth

One way to avoid sunscald on pepper fruits is to feed regularly during young growth. If your plants don’t get a good start to the season, they may have smaller leaf canopies. This means more light can reach the peppers once they begin growing.

Provide plenty of nitrogen, phosphorus and potassium, as well as calcium and magnesium. Ground soil often contains everything your plants need, but if you grow in pots, supplemental fertilizer is helpful.

Fox Farm makes a great trio of fertilizers, one for each stage of plant growth. Follow a rigorous feeding schedule from day one!

Learn more about fertilizing peppers in our article here.

Grow varieties with shading leaves

Hot, sunny days can be great for pepper plant development. After all, peppers require lots of sunlight to grow at their best! However, these sunny days are when peppers are most vulnerable to sunscald.

Some varieties of pepper plants have better leaf coverage than others. When choosing which variety to grow, consider how well the canopy will shade the developing fruits.

For example, bell peppers have large leaves, offering plenty of shade to the peppers below. However, some ornamental pepper varieties have much smaller leaves.

Other varieties have peppers that grow vertically, breaching the leaf canopy. This leaves room for the sun to penetrate and hit the fruits directly. However, in my experience, upward-growing peppers rarely get severe sunscald, as they have adapted to the exposure.

Space Plants Properly

Pepper plants should be spaced at a distance so that the plants touch each other slightly. Each plant will help provide shade to the next pepper in the row, helping to protect all of the fruits from direct sun exposure. In general, 18-24 inch spacing is best for most pepper varieties.

Provide alternate shade

When you are planning your garden, it is important to consider where each plant should go. Peppers are relatively short and require lots of sunlight. Usually, you’ll want to keep them out in the sun as long as possible.

However, while your plants are still young and transitioning to the outdoors, providing some shade during the hottest part of the day can help. I have had success using shade cloth over our low tunnels for this purpose.

If you don’t want to use artificial shade, consider planting taller plants on the western side of your peppers. Tomatoes, sunflower, or various perennial plants can be used to cast partial shade during the more intense parts of the day.

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Sunscald on your peppers can be very disheartening to see. If you suspect that your plants may be at risk, take precautions early and save the peppers! As always, you learn a bit more each year you grow, so next year can be more successful.

Good luck, and if you have any questions, feel free to leave them below.