7 Causes of Tomato Leaves Curling: From Heat to Virus

Get to the bottom of the issue to treat your tomatoes quickly

Tomato leaves curling and yellowing

JJGouin / Getty Images

Twisted or curled leaves on tomato plants can be caused by environmental stress, chemical exposure, or biological factors. While curling leaves do not necessarily kill the plant, determining the cause, or combination of reasons, as early as possible is crucial. Because curling is often a gradual process, the quicker you take corrective action, the better. 

First, take a close look at the tomato plants and observe the plants over a few days to see if there is any progression: 

  • How many leaves are curling, just a few or all the leaves on the plant?
  • Are the curling leaves mainly old leaves, new growth, or both?
  • In what direction do the leaves curl, upwards or downwards?
  • Are other parts of the plant, including fruit, showing any symptoms? 

Here are seven reasons why your tomato plants are having trouble with curling leaves and what you can do to fix it. 

  • 01 of 07

    1. Problem: Planting Tomatoes Too Early

    Roma tomato seedlings
    Roma tomato seedlings

    Barbara Rich / Getty Images

    Tomatoes that have not been properly hardened off, or planted too early when the weather was still too cool, can suffer from leaf curl. It usually starts with the lower leaves curling upwards, then rolling inwards lengthwise. The leaves also become thick and leathery but typically remain green.

    How to Fix It:

    Make sure to plant tomatoes only when daytime temperatures consistently reach between 70 and 79 degrees Fahrenheit, and nighttime temperatures are no lower than 61 to 65 degrees Fahrenheit. 

    Continue to 2 of 7 below.
  • 02 of 07

    2. Problem: Heat, Drought, and Wind

    Curling Tomato Leaves
    Getty Images

    In extremely hot, dry, or windy weather, tomato leaves twist and curl upwards to protect themselves from further water loss. 

    How to Fix It:

    If you live in a hot or warm climate, plant tomatoes in a location where they are sheltered from strong, drying winds and receive some late afternoon shade.

    Regardless of your climate, always keep tomato plants well-watered. Once outdoors, tomato plants will need at least 1 inch of water each week from rainfall or watering. Watering should be done slowly and deeply, so the plants form deep roots. Mulch around their base, so the soil stays evenly moist. 

    Continue to 3 of 7 below.
  • 03 of 07

    3. Problem: Nutrient Imbalance

    Tomato plant with root ball inserted into pot with soil near watering can spout

    The Spruce / Colleen & Shannon Graham

    Tomatoes overfertilized with nitrogen may show upward curled leaves that are thicker and greener than usual and also lots of foliage instead of setting fruit. Low phosphorus might also lead to leaf curl.

    How to Fix It:

    Even though tomatoes are heavy feeders, fertilization must be balanced. After planting in well-nourished soil, tomato plants benefit from applying a balanced 5-10-5 NPK fertilizer a few times throughout the growing season. Avoid fertilizers high in nitrogen (the first number), or you'll have many bright green leaves and fewer tomatoes.

    The only reliable way to determine the nutrient content in the soil and find out how to remedy the imbalance is a soil test done in a specialized laboratory (your local Extension Office sells soil kits).

    Continue to 4 of 7 below.
  • 04 of 07

    4. Problem: Herbicide Drift

    Man spraying pesticides on weeds.

    Getty Images

    Tomato plants are susceptible to herbicide damage. If the tomato leaves are curling downwards and growing twistedly, they might have been exposed to drifting herbicides—not necessarily from your use, but it could be from neighbors treating their lawns or from farm fields in the area. When spraying glyphosate or 2,4-D, dicamba, and other hormone-type herbicides, even a wind speed of five miles per hour can lead to herbicide drift.

    How to Fix It:

    Once the herbicide drift has occurred, there is nothing to be done. Depending on the severity of the herbicide damage, the plant may recover, and the new growth may look normal. If the new growth continues to show herbicide damage, which in addition to curling leaves, might include white and splitting stems and deformed fruit, you will, unfortunately, have to pull the plants. 

    Continue to 5 of 7 below.
  • 05 of 07

    5. Problem: Herbicide Residue in Mulch and Compost

    Mulching Tomato Plants
    Let the soil warm, before you spread mulch around your tomato plants. Photo: © Marie Iannotti.

    If you use mulch or compost from a third-party source and the leaves of your tomato plants become cupped or in any other way distorted, the reason might be residue from herbicides such as aminopyralid or clopyralid, the active ingredients in weed killers used by farmers. These chemicals remain on treated hay and hay products, grass clippings, manure, and compost for many months. Cows and horses feed on that hay and then pass it on via the manure.

    How to Fix It:

    To prevent this, make sure to get manure or compost only from reliable sources that don’t use these herbicides or use chicken manure, which does not have the problem. 

    Continue to 6 of 7 below.
  • 06 of 07

    6. Problem: Tomato Viruses

    Tomato spotted wilt virus is one of the many viruses that causes leaf curl
    Tomato spotted wilt virus is one of the many viruses that causes leaf curl

    Miyuki Satake / Getty Images

    If a virus causes curling tomato leaves, pinpointing it is rather tricky as numerous viruses can cause tomato leaf curling and stunted growth. The additional symptoms vary in each virus, and the transmission method differs. 

    Two common viruses that cause tomato leaf curl are tomato yellow leaf curl virus and tomato mosaic virus. Whiteflies transmit tomato yellow leaf curl virus. New leaves become cupped and turn pale green. The leaf edges turn yellow, and the undersides of the leaves may turn purplish. The plant's entire growth is stunted, and fruit production is poor.

    Tomato mosaic virus is transmitted from seed, grafting, human handling, and tobacco products. In addition to curling, the leaves become mottled, new leaflets are small and infected fruit is brown inside. The virus is a concern throughout the growing season. 

    Both viruses are major diseases causing havoc worldwide, including in the U.S. The mosaic virus is exceptionally hardy, surviving in plant debris for over 100 years.

    How to Fix It:

    To reduce the whitefly feeding that causes tomato yellow leaf curl virus, use reflective mulches (aluminum or silver-colored) between rows. To repel whiteflies and reduce feeding, mix a solution of 0.25 to 0.5% oil spray (2 to 4 teaspoons of horticultural or canola oil with a few drops of dish soap per gallon of water) and apply weekly. Remove plants and bag them for disposal at the end of the growing season. Consider rotating crops the next growing season.

    Because tomatoes are in the same plant family as tobacco (nightshades), tobacco users can transmit a mosaic virus to their tomato plants by touching them. Don’t allow smoking near your garden, and wash your hands or glove them before tending tomatoes if you are a smoker.

    A vital step to prevent your plants from getting infected is to keep your garden weed-free because weeds are often host plants for insects that then transmit a virus to your tomato plants.

    Continue to 7 of 7 below.
  • 07 of 07

    7. Problem: Broad Mites

    Septoria lycopersici (Septoria Leaf Spot). Ascomycota. Common fungal leaf disease of tomatoes. Tomato leaf showing small brown spots characteristic of the disease and some chlorosis or yellowing. Franklin County. Ohio. USA
    Matt Meadows / Getty Images

    When broad mites feed on young tomato leaves and flowers, they inject toxins into the plant that causes the leaves to twist and become distorted severely. The mites are so tiny that they cannot be detected with the naked eye and even a magnifying glass; only the damage will indicate their presence.

    If the infestation is severe, the underside of leaves and fruit might also turn bronze or russet in color.

    How to Fix It:

    Broad mites may come from infested greenhouse plants, so buy only plants from reliable suppliers.

    You can use a sulfur-based miticide to combat a moderate broad mite infestation. Read the label instructions carefully, as some tomato cultivars cannot tolerate treatment with sulfur. Organic alternatives to miticides are horticultural oils and insecticidal soaps.

    If the damage is severe, pull up the plants and dispose of them.

  • How can I prevent tomato plant leaves from curling?

    Pay close attention to your tomato plants' environmental conditions, like the temperature and moisture. Avoid using herbicides near your plants and treat insect issues immediately.

  • Should I remove curling tomato leaves?

    Removing curling tomato leaves is usually not necessary. Some leaves will uncurl as the health of the plant improves. If the plant is infested with disease or insects, discard it to prevent the spread of the problem.

  • Do curling leaves mean the tomato plant is dying?

    Your tomato plant may look bad, but curling leaves only sometimes means it could die or fruit production may reduce. Keep an eye on the plant, follow the care recommendations, and conditions may improve.

Originally written by
Nadia Hassani
Nadia Hassani

Nadia Hassani is a a Penn State Master Gardener with nearly 20 years of experience in landscaping, garden design, and vegetable and fruit gardening.

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  1. Tomato Leaves Rolling? Clemson University Home and Garden Information Center

  2. Tomato Leaves Rolling? Clemson Cooperative Extension Home & Garden Information Center.

  3. What Makes Tomato Leaves Twist or Curl. Texas A&M AgriLife Extension Service.

  4. Yan Z, Wolters AMA, Navas-Castillo J, Bai Y. The global dimension of tomato yellow leaf curl disease: current status and breeding perspectives. Microorganisms. 2021;9(4):740.

  5. Vegetable Crops: Virus diseases and disorders of tomato. Cornell University.