Curled leaves usually mean your tomato plant is either too dry, too hot, or dealing with a pest or disease

Tomato leaves curl for several reasons, and the cause matters because the fix is different for each one. The most common culprits are underwatering, heat stress, spider mites, early blight, and a virus called tomato yellow leaf curl. You can usually figure out which one by looking at the rest of the plant and the pattern of the curl — whether the whole leaf rolls inward, whether the edges brown, whether you see webbing or spots, and whether new growth comes in curled or only older leaves are affected.

The good news is that most causes are preventable, and many are reversible if you catch them early. The bad news is that waiting too long — especially with disease — can kill the plant or spread the problem to your other tomatoes.

Key Takeaways

  • Underwatering and heat stress cause the leaf edges to curl inward as the plant tries to reduce water loss, and both are fixed by watering deeply and mulching.
  • Spider mites cause fine webbing on the undersides of leaves and tiny yellow spots, and they thrive in hot, dry conditions where you are not watering the foliage.
  • Early blight starts with brown spots on lower leaves and causes them to curl and drop, and spreads through soil splash and wet foliage, so water at the base only.
  • Tomato yellow leaf curl virus causes new leaves to come in small and curled, and is spread by whiteflies — there is no cure, so remove the plant to stop the spread.
  • The fastest way to know which problem you have is to check the undersides of leaves for pests, look for spots or discoloration, and note whether the curl started on old leaves or new growth.

Underwatering and heat stress: the most common reason

When soil dries out too much between waterings, tomato leaves curl inward at the edges as the plant's way of reducing the surface area that loses water to the air. This is called leaf roll, and it happens fastest in hot weather when the plant is losing water through its leaves faster than the roots can pull it up from the soil. The curled leaves often feel papery and may turn slightly brown at the very edges.

The fix is to water deeply — soak the soil around the base of the plant until water runs out the drainage holes — and do it early in the morning so the plant has water available before the heat of the day. Mulch around the base with 2 to 3 inches of wood chips or straw to keep the soil cooler and reduce evaporation. If you are in a very hot climate or your tomato is in a pot, you may need to water every day or even twice a day during peak summer.

One thing to watch: if you let the plant dry out severely and then water it heavily all at once, the sudden influx of water can cause the fruit to crack. Water consistently rather than in feast-or-famine cycles. If the leaves are already curled from drought, they will not uncurl — new growth will come in normal — but consistent watering will prevent it from getting worse.

Spider mites: tiny pests that thrive in dry heat

Spider mites are so small you usually cannot see them without a magnifying glass, but you can see their damage and their webbing. Look at the undersides of the curled leaves: if you see fine, silky webbing and tiny yellow or tan spots on the leaf surface, you have spider mites. The leaves may curl, turn yellow, and eventually drop. The plant looks dusty or speckled.

Spider mites love hot, dry conditions — they are worst when the air is dry and you are not watering the foliage. The fix is to spray the undersides of the leaves with a strong stream of water from the hose every few days to knock the mites off and raise the humidity around the plant. If that does not work within a week, use neem oil or insecticidal soap, spraying the undersides thoroughly and repeating every 7 to 10 days for at least three applications. Always spray in the early morning or late evening, not in direct sun.

Prevention is easier than treatment: water the soil at the base only (not the foliage) to keep the leaves dry during the day, but mist the foliage in the early morning or evening to raise humidity, which spider mites hate. Space plants far enough apart that air flows between them.

Early blight: a fungal disease that spreads through water

Early blight is a fungal disease that starts on the lowest leaves of the plant and works its way up. You will see brown spots with concentric rings (like a target) on the lower leaves first. The leaves curl, turn yellow around the spots, and eventually drop off. The disease spreads through water — rain splash, overhead watering, or even touching wet leaves — so it gets worse the more you wet the foliage.

If you catch it early, remove the affected leaves by pinching or cutting them off and throwing them in the trash (not the compost). Disinfect your pruners with rubbing alcohol between cuts so you do not spread the disease to other parts of the plant. Water only at the base of the plant, never overhead, and water early in the morning so any splash dries quickly. Remove the lowest 6 to 12 inches of foliage from the plant as a preventive measure — this is the zone where the disease starts.

If the disease has already spread to many leaves, you can use a fungicide containing copper or chlorothalonil, following the label directions exactly. Once the plant is heavily infected, fungicide will slow it down but not stop it. The plant may still produce fruit, but it will be stressed and produce less.

Tomato yellow leaf curl virus: a disease with no cure

Tomato yellow leaf curl virus (TYLCV) causes new leaves to come in small, curled, and yellowed, often with a purple tint on the undersides. The plant stops growing, flowers drop, and fruit does not set. Unlike early blight, the curling starts on new growth at the top of the plant, not the old leaves at the bottom. The virus is spread by whiteflies — tiny white insects that cluster on the undersides of leaves.

There is no cure for a virus. Once a tomato plant has TYLCV, it will not recover. The best thing to do is remove the plant entirely and throw it in the trash to prevent whiteflies from spreading the virus to your other tomatoes. If you want to grow tomatoes in the same spot next year, look for varieties labeled TYLCV-resistant — many modern tomato varieties have been bred to resist this virus.

To prevent the virus in the first place, control whiteflies by spraying neem oil or insecticidal soap on the undersides of leaves every 7 to 10 days during the growing season. Remove any weeds around your tomato bed, because whiteflies live on many common weeds and use them as a stepping stone to your plants. If you see a tomato plant with TYLCV symptoms in a neighbor's garden, keep your distance — whiteflies can travel between yards.

How to tell which problem you have

Start by looking at the undersides of the curled leaves. If you see fine webbing and tiny yellow spots, it is spider mites. If you see nothing on the undersides but brown spots with rings on the upper surface of lower leaves, it is early blight. If the new growth at the top of the plant is small, curled, and yellowed, and you see tiny white insects on the undersides, it is TYLCV.

If the leaves are curled but otherwise look normal — no spots, no webbing, no discoloration — and the curling is worst during the hottest part of the day, it is almost certainly underwatering or heat stress. Check the soil: if it is dry an inch below the surface, water deeply. If the soil is moist but the plant is still curled, it is heat stress, and mulching will help more than extra water.

Take a photo of the curled leaves and the undersides if you can, and keep notes on when the curling started and which leaves are affected. This information will help you figure out the cause and decide whether to treat the plant or remove it.

Preventing leaf curl before it starts

Most leaf curl problems can be prevented with consistent care. Water deeply and regularly — tomatoes need about 1 to 2 inches of water per week, depending on heat and rainfall. Water at the base of the plant only, never on the foliage, to keep the leaves dry and prevent fungal disease. Mulch around the base to keep the soil cool and moist.

Space plants 24 to 36 inches apart so air flows between them, which reduces humidity around the foliage and makes it harder for fungal diseases and spider mites to take hold. Remove the lowest leaves as the plant grows — this removes the zone where early blight starts. If you live in an area where TYLCV is common, choose resistant varieties from the start.

Watch your plants regularly, especially the undersides of the leaves. The earlier you catch a problem, the easier it is to fix. A few curled leaves on an otherwise healthy plant is usually not a crisis, but if curling spreads quickly or the plant stops growing, act right away.

Frequently Asked Questions

Can a tomato plant recover from curled leaves?

It depends on the cause. If the curling is from underwatering or heat stress, new growth will come in normal once you fix the watering. If it is from spider mites or early blight, the curled leaves will not uncurl, but you can stop the spread and save the plant. If it is TYLCV, the plant will not recover — you need to remove it.

Should I remove all the curled leaves?

Not necessarily. If the curling is from heat or drought, leave the leaves alone — they are still photosynthesizing and feeding the plant. If the leaves have spots or signs of disease, remove them. If they are severely curled and brown, they are not doing much good, so you can remove them to reduce the disease load on the plant.

Can I use the same soil next year if my tomato had early blight?

Early blight spores live in soil and plant debris, so if you are growing tomatoes in the same bed, remove the top few inches of soil or add fresh compost on top. Do not compost the diseased plant material — throw it in the trash. If you grow in pots, dump out the old soil and use fresh potting mix.

What is the difference between early blight and late blight?

Early blight starts on lower leaves with brown spots that have rings, and spreads slowly. Late blight starts on any leaf and spreads very fast, causing large water-soaked spots and a white mold on the undersides. Late blight is much more serious and can kill a plant in days. Both are fungal and spread through water, so the prevention is the same: water at the base only.

Do I need to throw away fruit from a plant with curled leaves?

No. Fruit from a plant with early blight or spider mites is safe to eat — wash it well. Fruit from a plant with TYLCV is also safe, but the plant will not produce much. If the fruit itself has spots or damage, cut away the bad part and use the rest.