The most common causes of curling tomato leaves
Tomato leaves curl for three main reasons: too little water, too much heat, or a pest or disease problem. The curl pattern and the rest of the plant's condition tell you which one is happening. Underwatered plants curl inward and feel papery; heat-stressed plants curl to reduce water loss; and pest damage or disease shows other signs alongside the curl—yellowing, spots, or visible insects.
Identifying which cause is at work matters because the fix is different for each one. A plant that needs water needs a deep soak, not a spray. A plant in extreme heat needs shade cloth, not more water. A plant with spider mites needs miticide or neem oil. Treating the wrong problem wastes time and can make things worse.
Key Takeaways
- Underwatered tomato plants curl their leaves inward and feel dry and papery to the touch, and the soil will be hard and pulling away from the pot edge.
- Heat stress causes leaves to curl upward or inward as the plant tries to reduce water loss, and happens most often when temperatures stay above 85°F during the day or 75°F at night.
- Spider mites, whiteflies, and aphids all cause curling leaves and leave visible damage like webbing, yellowing, or sticky residue on the undersides of leaves.
- Tomato yellow leaf curl virus and fusarium wilt cause curling along with stunted growth, yellowing, and wilting that does not recover after watering.
- The first step is always to check soil moisture and look at the undersides of leaves for insects before assuming heat or disease is the problem.
Underwatering and soil moisture problems
Underwatered tomato plants curl their leaves inward, and the leaves feel thin and papery rather than firm. The soil will be hard, compacted, and often pulling away from the sides of the pot. If you water and the water runs straight through without soaking in, the soil has dried out so much that it has become hydrophobic—water-repellent. This is common in container plants that have dried out completely at least once.
The fix is a slow, deep soak. Water the base of the plant, not the leaves, and let water run through the drainage holes for at least 30 seconds. Do this once, then wait a few hours and water again if the soil is still dry below the surface. Tomato plants need consistent moisture—the soil should feel like a wrung-out sponge, not soggy and not bone-dry. In hot weather, container plants may need water every day. In-ground plants need deep watering two or three times a week depending on rainfall and heat.
If the soil is hydrophobic, soak the entire pot in a bucket of water for 15 to 20 minutes, or add a drop of dish soap to your watering can—the soap breaks the water's surface tension and helps it soak in. Once the plant recovers, the leaves will uncurl within a few days.
Heat stress and temperature extremes
Tomato plants curl their leaves when temperatures stay above 85°F during the day or 75°F at night. The plant is not dying—it is protecting itself by reducing the surface area of its leaves so less water evaporates. The leaves curl upward or inward, and the plant may drop flowers or fail to set fruit even if it is getting enough water.
Heat stress is hardest to manage in containers, which heat up faster than in-ground soil. Move potted plants to a spot with afternoon shade, or drape shade cloth over the plant—30 to 50 percent shade cloth is enough. Water more often in heat; container plants may need water twice a day. Mulch around the base with 2 to 3 inches of straw or wood chips to keep the soil cooler. In-ground plants benefit from mulch as well, and from consistent deep watering early in the morning.
Once temperatures drop below 85°F at night, the plant will stop curling new leaves and the existing curled leaves will not straighten—they will stay curled for the rest of their life. But new growth will be normal. If your plant is in a very hot spot and temperatures are not expected to drop, shade cloth is your best option.
Spider mites, whiteflies, and other pests
Spider mites are the most common pest cause of curling tomato leaves. They are tiny—barely visible to the naked eye—and they live on the undersides of leaves, where they suck out plant juices. Infested leaves curl, turn yellow or bronze, and may have fine webbing between the leaf and stem. The damage starts at the bottom of the plant and moves upward.
Whiteflies cause similar curling and yellowing. If you brush the leaf, a cloud of tiny white insects will fly up. Aphids cluster on new growth and cause leaves to curl and become sticky with honeydew, a sugary substance the insects excrete. All three pests thrive in hot, dry conditions and spread quickly in summer.
Check the undersides of curled leaves with a magnifying glass or by holding a leaf up to the light. If you see webbing, insects, or sticky residue, spray the plant with neem oil or insecticidal soap, following the label directions. Spray the undersides of leaves thoroughly. Repeat every 7 to 10 days for three applications. In severe cases, miticide made for spider mites works faster than neem oil. Water the plant well before spraying, and spray in the early morning or late evening to avoid leaf burn.
Tomato yellow leaf curl virus and other diseases
Tomato yellow leaf curl virus causes leaves to curl upward, turn yellow, and become stiff and brittle. The plant is stunted and produces little or no fruit. The virus is spread by whiteflies, so controlling whiteflies is the best prevention. Once a plant has the virus, there is no cure—the plant must be removed and destroyed. Do not compost it.
Fusarium wilt is a soil-borne fungus that causes leaves to curl, yellow on one side of the plant first, and wilt even when the soil is wet. The plant may recover temporarily after watering, but wilting returns and worsens. Cut open the stem near the base—if the inside is brown or discolored, it is fusarium. Remove the plant and do not plant tomatoes in that spot for at least three years, as the fungus lives in the soil.
Early blight and septoria leaf spot cause brown or gray spots on leaves along with some curling and yellowing. These fungal diseases start on lower leaves and move upward. Remove affected leaves, improve air circulation by pruning lower branches, and avoid wetting the leaves when you water. Fungicide sprays containing copper or sulfur can slow the spread.
How to tell the difference at a glance
| Cause | Leaf feel and appearance | Other signs | First step |
|---|---|---|---|
| Underwatering | Papery, thin, inward curl | Hard, dry soil; soil pulling from pot edge | Deep soak the soil |
| Heat stress | Firm, upward or inward curl | Soil is moist; no insects; temps above 85°F | Provide afternoon shade |
| Spider mites | Curled, yellowing; fine webbing visible | Webbing between leaf and stem; tiny insects on undersides | Spray undersides with neem oil |
| Whiteflies | Curled, yellowing; sticky residue | Cloud of white insects when leaf is brushed | Spray with insecticidal soap |
| Tomato yellow leaf curl virus | Curled upward, stiff, yellow | Stunted plant; little or no fruit; whiteflies present | Remove and destroy plant |
| Fusarium wilt | Curled, yellowing on one side | Wilting even when soil is wet; brown discoloration inside stem | Remove plant; do not replant tomatoes there |
Prevention and long-term care
Most curling problems are preventable with consistent watering and good growing conditions. Water deeply and regularly—the soil should stay moist but not waterlogged. In containers, check soil moisture daily in summer. Mulch around the base to keep soil temperature and moisture stable. Space plants far enough apart for air to move between them, which reduces pest and disease pressure.
Choose disease-resistant varieties when possible—look for varieties marked VF or VFNT on the label, which means they resist verticillium and fusarium wilts. Remove lower leaves once the plant is established to improve air circulation and reduce fungal disease. Scout for pests weekly by checking the undersides of leaves. Catching spider mites or whiteflies early, before they spread, makes them much easier to control.
In very hot climates, plant tomatoes where they get afternoon shade, or plan to shade them with cloth once temperatures consistently exceed 85°F. Consistent watering is more important than any other factor—a plant that never dries out is more resilient to pests, disease, and heat stress than one that swings between wet and dry.
Frequently Asked Questions
Can curled leaves straighten out once they uncurl?
No. Once a leaf curls from heat stress or underwatering, it stays curled for the rest of its life. The plant will produce new, normal leaves once the problem is fixed. You can remove curled leaves if they look bad, but it is not necessary—the plant will shed them naturally as new growth takes over.
Should I remove leaves that are curling from disease?
Yes, if the curling is caused by early blight, septoria leaf spot, or fusarium wilt. Remove the affected leaves and throw them in the trash, not the compost. Sterilize your pruning shears with rubbing alcohol between cuts to avoid spreading the disease to other parts of the plant.
What if my tomato plant has curled leaves but the soil is wet?
Check the undersides of the leaves for insects first. If you see webbing or tiny bugs, treat for spider mites. If the soil is wet and there are no insects, the problem is likely heat stress or disease. Feel the leaves—if they are firm and the plant is otherwise healthy, it is probably heat. If leaves are yellowing or wilting, check for brown discoloration inside the stem.
Can I use the same fungicide for all leaf diseases on tomatoes?
No. Early blight and septoria leaf spot respond to copper or sulfur fungicides. Fusarium wilt is soil-borne and cannot be treated with fungicide—the plant must be removed. Tomato yellow leaf curl virus has no fungicide treatment. Always identify the disease before spraying.
Is it safe to eat tomatoes from a plant with curled leaves?
Yes, as long as the curling is from underwatering, heat stress, or pest damage. Do not eat fruit from a plant with tomato yellow leaf curl virus or fusarium wilt—remove and destroy the entire plant. Fruit from plants with early blight or septoria leaf spot is safe to eat, but wash it well.