How to Prevent Sunscald and Cracking in Tomatoes

During the hot season, many growers face serious challenges that affect the quality and market value of their tomatoes. Some of the most common problems include sunscald, fruit cracking, and uneven ripening.

Sunscald happens when the tomato fruit is exposed to direct sunlight for long periods. It causes white or pale yellow patches on the skin, much like a sunburn on human skin.
Cracking, also called fruit splitting, usually occurs when the plant absorbs water too quickly after a dry spell, causing the skin to burst.
Uneven ripening and fruit rot are also common during periods of extreme heat or poor water management.

These issues can lead to lower yields, rejected produce, and loss of income. Fortunately, there are simple and affordable strategies to prevent these problems. This article explains how commercial and greenhouse tomato growers can protect their crops and maintain high-quality fruits throughout the season.

What Causes Sunscald and Cracking?

Sunscald is caused by too much direct sunlight on the tomato fruit, especially when there is not enough leaf cover to provide shade. This often happens when the plant is pruned too heavily or the leaves are damaged by pests or disease.

Cracking, on the other hand, is caused by irregular watering. When the plant goes through a dry period and suddenly receives too much water—either through rainfall or overwatering—the fruit swells quickly, and the skin splits. These splits allow bacteria and fungi to enter the fruit, leading to rotting.

Poor nutrition and inconsistent care can also lead to uneven ripening, especially in high temperatures. All of these problems are avoidable if you follow the right growing practices.

Simple Ways to Prevent Sunscald and Cracking in Tomatoes

1️⃣ Maintain a Healthy Leaf Canopy: One of the best ways to protect tomatoes from sunscald is to maintain a healthy leaf canopy. Leaves act as natural shade for the fruits. Avoid removing too many leaves during pruning. Leave enough foliage around the fruit clusters to block harsh sunlight, especially during midday.

2️⃣ Install Shade Netting in Greenhouses or High Tunnels: If you are growing tomatoes in a greenhouse or high tunnel, consider using shade nets. A 30% to 50% shade cloth can help reduce the temperature inside the structure and prevent fruit from overheating.

3️⃣ Mulch and Drip Irrigate for Consistent Moisture: Consistent watering is also very important. Use drip irrigation or water deeply two to three times per week. Avoid watering too lightly or skipping days, as this causes stress to the plant. Applying mulch—such as straw, dry grass, wood chips, or black plastic—will help the soil retain moisture and stay cool, reducing the risk of cracking.

4️⃣ Monitor Soil Moisture Daily: Checking the soil moisture daily can help you make better watering decisions. You can use a soil moisture meter, or simply press your finger into the soil. If it feels dry more than two inches deep, it’s time to water. If it’s still moist, you can wait.

5️⃣ Use Calcium-Rich Fertilizers: Tomatoes also need calcium to develop strong fruit skins. Cracking and blossom-end rot are often linked to calcium deficiency. Apply calcium-rich fertilizers like calcium nitrate, crushed eggshell tea, or bone meal, especially when the plant begins to fruit.

6️⃣ Choose Crack-Resistant Varieties: Another smart step is to choose tomato varieties that are resistant to cracking for next planting season. Varieties such as Roma VF, Carmen F1, and UC82B are good examples. These types of tomatoes have thicker skin and are better able to handle stress from water or heat.

7️⃣ Harvest Frequently: Finally, don’t wait for them to ripen fully on the vine, especially during hot weather. Pick the fruit when it is full-sized and has started to change color. This prevents overripening and splitting and allows you to finish ripening the fruit in a cool, shaded place after harvest.

Greenhouse vs. Open-Field: Which Approach Works Best?

In greenhouses, you can control the environment more easily. Shade nets, drip irrigation, and ventilation systems help protect the crop. In open fields, you depend more on natural methods like mulch, pruning, and variety selection. Both methods can produce high-quality tomatoes if you manage heat and moisture correctly.

Conclusion

Sunscald and cracking can be frustrating, but they don’t have to ruin your harvest. By maintaining healthy foliage, watering consistently, choosing the right varieties, and managing heat exposure, you can protect your tomatoes and increase your profits.

Good tomato farming is not just about growing a lot—it’s about growing quality fruits that sell well. With these simple changes, your crop can survive the heat and thrive in any environment.

Join the Wise Farmer Tomato Course

Are you ready to take your tomato farming to the next level? Join the Wise Farmer Tomato Production Course. You’ll learn everything from soil preparation to post-harvest handling, and how to consistently produce top-grade tomatoes for local and export markets.