—
Few things send tomato growers into a panic quite like curling leaves. One day your plant looks fine, the next day the leaves are doing gymnastics, and you’re googling frantically at 2am wondering if your plant is dying.
Deep breath. Curling leaves are usually NOT a death sentence. Let’s figure out what’s happening and fix it.
## Types of Leaf Curling (Yes, It Matters)
How your leaves are curling tells you a lot about the problem:
Curling UP (edges rolling upward): Usually environmental stress
Curling DOWN (leaves cupping downward): Often overwatering or disease
Curling INWARD (leaves rolling lengthwise): Can be pests, herbicide drift, or genetic
Let’s troubleshoot by type.
## Reason #1: Heat Stress (Curling UP)
What it looks like:
Leaves curl upward along the edges, sometimes rolling into themselves. Plant otherwise looks okay. Happens during hot weather.
Why it happens:
When it’s blazing hot (90°F+), tomato plants curl their leaves to reduce surface area exposed to sun. It’s self-protection to conserve water.
How to tell this is your problem:
– Happens during heat waves
– Leaves uncurl in the evening/cooler weather
– Plant is otherwise healthy
– No pests or disease visible
The fix:
This is often NORMAL and not something to fix. But you can help:
– Provide afternoon shade (shade cloth, umbrellas)
– Mulch heavily to keep roots cool
– Water consistently (but don’t overwater!)
– Mist plants in extreme heat (only in early morning)
Leave the leaves alone—they’ll uncurl when temps drop.
## Reason #2: Overwatering (Curling DOWN)
What it looks like:
Leaves curl downward and may look swollen or puffy. Soil is constantly wet. Plant may be yellowing.
Why it happens:
Too much water drowns roots, preventing oxygen uptake. Leaves curl and plants show distress.
How to tell:
– Soil is always wet or soggy
– Yellow leaves + downward curling
– Stems near soil may look dark or mushy
– You water daily or whenever you remember
The fix:
– Let soil dry out between waterings
– Stick your finger 2 inches into soil—only water if dry
– Improve drainage (add perlite, sand, or raise beds)
– Ensure containers have drainage holes
– Water deeply but less frequently
## Reason #3: Underwatering (Curling INWARD/UP)
What it looks like:
Leaves curl inward or roll up tightly. Leaves may be crispy or dry. Obvious wilting.
Why it happens:
Plant is conserving moisture. Curling reduces surface area and water loss.
How to tell:
– Soil is bone dry
– Plant is wilted and sad-looking
– Leaves feel dry and brittle
– You honestly can’t remember the last time you watered
The fix:
– Water thoroughly until it drains from the bottom
– Set phone reminders to water
– Mulch to retain moisture
– Water in morning to give plants all-day hydration
Most plants bounce back quickly once watered.
## Reason #4: Pests (Various Curling Patterns)
Several pests cause leaf curling:
Aphids:
Tiny green, black, or white insects. Suck plant sap. Cause leaves to curl and distort. Often found on new growth and undersides of leaves.
The fix:
– Blast off with strong spray of water
– Insecticidal soap or neem oil
– Introduce ladybugs (natural predators)
– Check plants regularly
Spider mites:
Microscopic pests. Look for fine webbing and stippled yellow leaves. Cause leaves to curl and dry out.
The fix:
– Spray with water (they hate moisture)
– Neem oil or insecticidal soap
– Remove heavily infested leaves
Whiteflies:
Tiny white flies that cloud up when you disturb plant. Cause curling and yellowing.
The fix:
– Yellow sticky traps
– Insecticidal soap
– Neem oil
– Spray with water
Psyllids (Tomato Psyllids):
Cause severe leaf curling, yellowing, and stunted growth. More common in western US.
The fix:
These are serious. Remove affected plants. Use row covers to prevent. Choose resistant varieties.
## Reason #5: Diseases (Usually Curling + Other Symptoms)
Leaf curl virus (Tomato Yellow Leaf Curl Virus – TYLCV):
Causes severe upward and inward curling, yellowing, stunted growth. Spread by whiteflies.
The fix:
No cure. Remove infected plants. Control whiteflies aggressively. Choose virus-resistant varieties (look for TYLCV on seed packets).
Early Blight:
Can cause some curling along with dark spots with target-like rings on lower leaves.
The fix:
Remove affected leaves. Improve air circulation. Fungicide if severe. Mulch to prevent soil splash.
Verticillium or Fusarium Wilt:
Causes yellowing and curling, usually on one side of plant first. Eventually leads to wilting and death.
The fix:
No cure. Remove plants. Don’t plant nightshades in that spot for 3-4 years. Choose resistant varieties (look for V or F on seed packets).
## Reason #6: Herbicide Drift (Curling INWARD/TWISTED)
What it looks like:
Bizarre, twisted, cupped leaves. Growth looks deformed. Stems may be thick and distorted.
Why it happens:
Herbicides (especially broadleaf weed killers like 2,4-D) drift through the air or contaminate mulch/compost. Even small amounts cause dramatic leaf distortion.
How to tell:
– Multiple plants affected similarly
– Someone sprayed weed killer nearby recently
– You used hay/straw/compost that might have been contaminated
– Leaves look weirdly twisted, not just curled
The fix:
– If drift, there’s nothing to do but wait. New growth should be normal.
– If contaminated mulch, remove it immediately
– Don’t use grass clippings from lawns treated with herbicides
– Talk to neighbors about spray timing (and ask them to warn you!)
Most plants recover, but growth may be stunted for a while.
## Reason #7: Physiological Leaf Roll (Curling UP—But Normal!)
What it looks like:
Lower to middle leaves roll upward along the edges. No other symptoms. Plant is healthy, growing, producing fruit.
Why it happens:
Some varieties (especially indeterminates) just DO this. It’s genetic. It’s not a problem.
How to tell:
– Only older leaves affected
– Plant is otherwise thriving
– Happens consistently, not suddenly
– Especially common in hot weather
The fix:
Nothing! It’s normal. Ignore it and enjoy your tomatoes.
## Reason #8: Nitrogen Excess (Curling + SUPER GREEN Leaves)
What it looks like:
Dark green, lush foliage. Leaf edges may curl slightly. Lots of growth but few flowers.
Why it happens:
Too much nitrogen (from over-fertilizing or fresh manure) causes excessive leaf growth at the expense of fruit.
The fix:
– Stop or reduce nitrogen fertilization
– Switch to fertilizer higher in phosphorus and potassium (5-10-10)
– Be patient—plant will eventually balance out
– Next time, use aged manure, not fresh
## How to Diagnose YOUR Curling Problem
Step 1: Check the weather
Hot? Probably heat stress.
Cool and wet? Possibly overwatering.
Step 2: Check the soil
Wet = overwatering
Dry = underwatering
Step 3: Inspect for pests
Look under leaves, on stems, on new growth. Use a magnifying glass if needed.
Step 4: Look for other symptoms
Spots on leaves? Probably disease.
Weird twisted growth? Possibly herbicide.
Just curling but otherwise healthy? Could be physiological or heat stress.
Step 5: Review your care
When did you last water? Fertilize? Spray anything? Use new mulch?
## When to Worry vs. When to Chill
Don’t panic if:
– Curling happens during a heat wave and uncurls at night
– Only lower, older leaves are affected and plant is otherwise thriving
– Curling resolves after adjusting watering
Take action if:
– Rapid spread to multiple leaves
– Other symptoms (spots, yellowing, wilting)
– Pests are visible
– Whole plant looks distressed
## Prevention Tips
Consistent watering: Avoid extremes
Proper fertilizing: Follow directions, don’t overdo it
Pest monitoring: Check plants weekly
Good airflow: Don’t overcrowd plants
Mulch: Keeps soil moisture consistent
Choose resistant varieties: Look for disease codes on seed packets (VFN, TYLCV, etc.)
## The Bottom Line
Curling leaves are your plant’s way of communicating. It’s saying:
“I’m too hot!” (heat stress)
“I’m drowning!” (overwatering)
“I’m thirsty!” (underwatering)
“Something’s eating me!” (pests)
“I’m sick!” (disease)
“What the hell did you spray near me?” (herbicide)
“This is just how I am, deal with it” (physiological)
Listen to your plant, troubleshoot systematically, and make ONE change at a time. Don’t water AND fertilize AND spray all at once—you won’t know what fixed it!
Most curling issues are fixable. Even the “serious” ones (like virus) teach you lessons for next season.
Your tomatoes are tougher than you think. Give them what they need, and those leaves will straighten out (or at least stop getting worse).
Now go check under those leaves for aphids. You know you want to. 🍅
