Why Are My Tomato Leaves Curling? A Diagnostic Walkthrough

Physiological leaf roll: usually nothing to fix

This is the version most gardeners see, and it is not a disease. The leaflets first cup upward, then roll inward toward the midvein, and the rolled tissue often feels thick and leathery while keeping a normal green color. Clemson notes it has minimal impact on fruit production and plant growth, and that indeterminate varieties are more prone than determinate ones.

It is triggered by stress rather than a pathogen: excessive soil moisture, high nitrogen, low phosphorus, heat, drought, severe pruning, root damage from cultivating too close, or transplant shock. It often appears as spring flips to summer. If the leaves are rolled but still green and the plant is flowering and setting fruit normally, the most likely answer is simply that the plant is stressed, and steady watering plus easing off heavy pruning usually settles it.

Rule out herbicide injury

Herbicide damage looks different from physiological roll, which is why the direction of the curl matters. With growth-regulator herbicides such as 2,4-D or dicamba, leaves tend to roll downward and the new growth becomes twisted, narrow, and distorted; stems may turn white and split, and fruit can be deformed. These products can drift from lawns or nearby fields, and contaminated compost, manure, straw, or grass-clipping mulch is another common route.

If your tomatoes suddenly show twisted, strappy new leaves after a nearby spray day or after adding mulch or compost, herbicide is a strong suspect. The injury cannot be reversed, though a plant may grow out of it if the dose was light. When in doubt, note what was applied nearby and ask your Extension office to help confirm rather than guessing.

When to suspect a virus

Virus is the least common of the three but the most important to identify, because there is no cure and infected plants are best removed. With tomato yellow leaf curl virus, spread by whiteflies, new leaves become cupped and pale green, and the whole plant may be stunted with yellow leaf edges and sharply reduced fruit. Tomato mosaic virus can also roll leaves, but adds mottled light-and-dark coloring, small leaflets, and internal browning of the fruit.

The tell is that virus symptoms travel with other problems, mottling, stunting, discolored fruit, rather than appearing as clean green rolled leaves on an otherwise vigorous plant. Because virus, herbicide, and physiological roll can look similar early on, treat any case with mottling or persistent twisted new growth as uncertain and confirm with your local Extension before pulling plants.

Sources

Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.

• Clemson HGIC - Tomato Leaves Rolling? — Leaf roll has three causes: physiological (upward cupping then inward roll, leaves stay healthy green, minimal impact on fruit, indeterminate types more prone), herbicide (downward rolling and twisted growth, white split stems, deformed fruit), and virus (cupped pale-green new leaves, mottling, stunting, poor fruit set).
• SDSU Extension - Why Are My Tomato Leaves Curled Up? — Leaf roll groups into physiological (heat, water, wind, pruning, transplant shock), chemical (2,4-D and dicamba drift causing C-shaped inward curl and twisting), and disease (viruses); physiological roll does not harm the plant.
• University of Missouri IPM - Tomato Leaf Curl — Physiological leaf roll is a common, non-damaging response to environmental stress, while herbicide injury and viral infections produce distinct distortion, twisting, or mottling that should be distinguished from it.

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