Tomatoes Can Sunburn—Here's What You Need To Know To Prevent Sunscald

Tomatoes love and need a lot of sunlight and heat to grow. But too much of a good thing can cause the plant to get sunscald–the plant equivalent of a sunburn. “Sunscald in tomatoes can happen in all parts of the country, but it is more prominent in the South where the days are longer and the weather is hotter,” says Greg Key, gardener and president of Hoss Tools in Georgia.

What is Sunscald?

Tomatoes need plenty of sunlight to produce fruit, typically around six to eight hours a day. Too much sun and heat can cause tomatoes to get sunscald. “Sunscald happens when the tomatoes are hit with the direct waves of the sun without any protection, similar to sunburn on us humans,” says Key. According to Jennifer McDonald, certified organic garden specialist and co-founder of Garden Girls, a garden design company based in Houston, Texas, she says sunscald occurs with “extreme heat coupled with direct sunlight.” 

If you’re experiencing a heat wave or increased temperatures, there’s usually no need to worry. “A few days of higher-than-normal temperatures usually don’t cause sunscald,” says McDonald.

What Sunscald Looks Like

Sunscald can affect the leaves as well as the fruit. “Leaves with white or brown spots, and tomatoes with cracks or patches of blotchy white, yellow, or gray spots are all indications of sunscald,” says McDonald. Fruit that is exposed due to over-pruning can also be more prone to sunscald. “For example, if you’ve spent the day pruning your tomato plants and removing diseased foliage, you’ll often see tomatoes in bunches that are exposed to direct sunlight,” says McDonald. “When the leaves are gone, so is the umbrella effect.” So before you go overboard with pruning tomato stems and leaves, think about how the foliage is providing natural shade. 

Why Planting Tomatoes Early in the South is Important

When you plant your tomatoes ensure they grow properly and reach all growth stages. As a guide, you want to plant after the last freeze in spring. “In the South, we plant our tomatoes right after Valentine’s Day to allow them enough time to pollinate, bear fruit, and ripen before the extreme heat takes over in late June,” says McDonald. “Once the extreme heat is upon us, tomato growth all but stops completely.” She says that’s when it’s time to harvest or remove the plants.

Choose Tomatoes that Thrive in Your Climate 

The type of tomato plant you grow is important to minimize the chance of sunscald. “In the South where sunscald is a serious problem, planting the correct type and variety can help with this issue,” says Key. He recommends two tomato plants: “Red Snapper and Hossinator are two varieties that thrive and have minimal sunscald.” He explains that both are determinate tomatoes that are bred to have little to no pruning, dense foliage, outstanding fruit size and to be very high in yield production. 

Oftentimes, bigger-sized tomatoes are more susceptible to sunscald. “Larger beefsteak tomatoes take longer to grow and have more surface area which means a higher chance of direct sunlight exposure and greater risk for sunscald,” says McDonald. If your USDA Zone has very hot summers, you may want to grow smaller-sized tomatoes. “In zones with exceptionally hot summers, choosing smaller indeterminate cherry tomatoes will result in better outcomes and less sunscald,” says McDonald.

How to Prevent Sunscald  

Sunscald can be prevented. “Sunscald is a physiological condition, unlike fungal diseases in tomatoes, which are harder to prevent and treat,” says McDonald. Here are two ways to reduce the chances of sunscald.

Use a Shade Cloth

Although tomatoes love the sun, putting up a shade cloth can help them out significantly during the hottest parts of the day. “This is a simple but effective way to ensure that fruit-bearing plants receive enough sunlight but are protected from the intensity of direct rays,” says McDonald. “There are a number of options when choosing shade cloth, with percentages ranging from 30-75% shade coverage. When in a pinch, an umbrella can provide shade to growing plants.”

Don’t Over-prune

Pruning helps promote fruit growth. But overdoing it can cause your tomato plants harm. “Over the years there’s been a growing practice to prune tomatoes heavily to maximize the size of fruit and produce more fruit per plant,” says Key. “This strategy certainly works, but the downside to the pruning method is you leave the fruit exposed to the sun, and that is when the damage occurs.” 

According to McDonald, “Pruning tomato plants can become quite addicting, but it’s beneficial to avoid over-pruning during the peak of summer.” She says that even sunburned leaves can provide protection to delicate fruit. Even crispy leaves are fine to leave on a tomato plant if fungal diseases aren’t present, she adds. 

Can You Eat Them?

Typically, you can eat a sunscalded tomato if there isn’t any mold. According to McDonald, “While they may look a little funky, they are still edible, assuming that the white patches have not become black, which could indicate mold.” 

Sometimes a tomato just has a yellow or white blemish. “If the sunscald is just a blotchy patch on the tomato that hasn’t blistered, it’s fine,” she says. “Cut around it and enjoy the rest of that juicy tomato!”

But there are some signs when you shouldn’t eat a sunscald tomato. “If your tomato looks sunken or blistered or has deep cracks that have exposed the flesh, you’re better off tossing it,” she says.