Plant Problem Diagnosis Key / Growing conditions

Growing conditions

Heat and light stress

Above about 90 °F (32 °C), or under more light than the plant can use, leaves curl to shed heat and the plant wilts at midday even when watered.

Tomato leaves curled and cupped from heat
Tomato leaves curled and cupped from heat Photo: Terri Dux, USDA NRCS Pacific Islands Area, Public domain, via Flickr

Signs

What favors it

Temperatures above the crop's range, lamps too close, low humidity with high leaf temperature, and dry soil.

Prevention

Often confused with

Growing conditionsDrought stress (underwatering) Growing conditionsLight bleaching NutrientToo much nitrogen

Sources

Why →

Treatment by crop

Cultural, biological and chemical options in the order to use them, and notes written for each crop.

Identification is free. Treatment is on the Home and Pro plans.

Open in the key See plans

Questions in the key that lead here

  1. Look the plant over, leaf undersides included. Are insects, mites, slugs, eggs, webbing or droppings on it?
    No, only damage or discoloration
  2. Where is the problem?
    Leaves
  3. What does the leaf damage look like?
    Shape change
  4. What has the leaf done?
    Edges curl up, the leaf folds like a taco

Not a match? Start the key or describe what you see.

More photos

Brown, brittle leaf edges on a prayer plant from heat and dry air
Brown, brittle leaf edges on a prayer plant from heat and dry air Photo: Lexilovescaffeine, CC0, via Wikimedia Commons
Sunburned grape leaf: bleached and browned where it took the full sun
Sunburned grape leaf: bleached and browned where it took the full sun Photo: Bauer Karl, CC BY 3.0, via Wikimedia Commons

More from university Extension: search Extension pages on heat and light stress, or find a plant diagnostic lab through your state's Extension.

Other growing conditions

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