By Azura · Updated June 2026 · Raised Garden Hub is reader-supported. When you buy through links on our site, we may earn an affiliate commission at no extra cost to you.
Curling tomato leaves are usually harmless — they’re the plant’s response to heat and water stress. If the leaves roll up but stay green and the plant keeps growing and fruiting, there’s nothing to fix. The causes that actually matter are herbicide damage and virus. Here’s how to tell them apart.
1. Heat & water stress (most common, harmless)
On hot days leaves roll upward and inward to reduce water loss, then relax by evening. Fix: water deeply and consistently, mulch to keep soil moisture even, and give afternoon shade in a heatwave. No action needed beyond good watering.
2. Wind or transplant shock
Strong wind or a recent transplant can curl leaves temporarily. Fix: shelter the plant; it recovers in a few days.
3. Over-pruning
Removing too many suckers and leaves at once stresses the plant. Fix: prune lightly and gradually.
4. Herbicide damage (the one to catch)
Leaves that curl and twist, with new growth distorted, often mean herbicide drift — or contaminated straw, manure, or compost (persistent herbicides like aminopyralid). Fix: stop using the suspect mulch/compost immediately; badly affected plants rarely recover.
5. Viral infection (less common)
Curling with yellowing, mottling, or stunting can be a virus (e.g. curly top, spread by leafhoppers). Fix: there’s no cure — remove infected plants to protect the rest.
Quick diagnosis
| Leaves are… | Likely cause | Action |
|---|---|---|
| Rolled up, green, plant healthy | Heat / water stress | Just water well — harmless |
| Curled and twisted/distorted | Herbicide damage | Stop using suspect mulch/compost |
| Curled and yellow/mottled/stunted | Virus | Remove the plant |
Most of the time it’s heat — keep watering consistent and your tomatoes will be fine. Pair them with the right companion plants and a deep raised bed for the healthiest plants.
Frequently asked questions
Why are my tomato leaves curling up?
The most common cause is heat and water stress — leaves roll upward to conserve moisture on hot days, then recover by evening. Other causes are wind, heavy pruning, herbicide drift, or, less often, a virus.
Should I worry about curling tomato leaves?
Usually not. If leaves roll up but stay green and the plant keeps growing and fruiting, it's just heat or water stress and harmless. Worry only if leaves are also twisted, discolored, or the plant is stunted — that points to herbicide damage or virus.
How do I stop tomato leaves from curling?
Water deeply and consistently, mulch to keep soil moisture even, provide afternoon shade in extreme heat, and avoid over-pruning. If you suspect herbicide-contaminated mulch or compost, stop using it.