What Causes My Tomato Plants Leaves to Curl?

Tomatoes are a popular vegetable crop in many gardens, but it can be frustrating to see your tomato plant leaves curling. There are several reasons why tomato leaves may curl, and it’s important to identify the cause so you can take appropriate action.

Overwatering

One common cause of leaf curling in tomato plants is overwatering. When the soil is constantly wet, the roots can become waterlogged and can’t absorb sufficient oxygen. As a result, the leaves may curl and become distorted. To avoid this, make sure you water your tomato plants deeply but infrequently, allowing the soil to dry out between watering sessions.

Underwatering

On the other hand, if you don't water your tomato plant enough, the leaves may also curl up. This is the plant's way of trying to preserve moisture in the leaves. When you water your tomato plant, make sure you give it enough water to soak the root ball. If the soil is too dry or the roots are too exposed, the plant may struggle to get enough water and the leaves may curl.

Temperature Stress

Tomato plants are sensitive to extreme temperatures. High temperatures above 90℉ (32℃) can cause tomato leaves to curl as the plant tries to conserve moisture. Similarly, when the temperature drops below 50 ℉ (10 ℃), the leaves may also curl as they attempt to protect the plant from the cold. If possible, move your tomato plants to a location where they can receive partial shade during the hottest part of the day or cover them during cold nights.

Pest Infestations

Pests such as spider mites, whiteflies, and aphids can also cause leaf curling in tomato plants. These pests suck sap from the plant, causing the leaves to curl and become discolored. To prevent infestations, consider spraying your plants with an insecticidal soap or neem oil, or use natural predators such as ladybugs and praying mantises to eliminate the pests.

Viral Infections

Finally, viral infections can also cause leaf curling in tomato plants. Some of the most common viruses that affect tomato plants include tomato mosaic virus, tomato spotted wilt virus, and tomato yellow leaf curl virus. Unfortunately, there is no cure for viral infections. To prevent the spread of the virus, remove and destroy affected plants and sanitize your gardening tools.

By understanding the different reasons for leaf curling in tomato plants, you can take steps to keep your plants healthy and thriving. Whether it's adjusting your watering schedule or addressing pest infestations, taking action early can help prevent more serious plant problems down the line.