Heat stress
Wilting, curling and dropped flowers in long hot spells.
What you'll see
- Leaves wilt in the afternoon heat, or curl, cup and roll inward.
- Leaf edges dry out and crisp, and sun-facing leaves may bleach or scorch.
- Flowers and young fruit drop, and leafy crops rush to flower.
- Young plants and plants in pots dry out and collapse fastest.
Why it happens
Long spells above about 86°F (30°C) make leaves lose water faster than the roots can supply it, and upset flowering.
How to fix it
- Water deeply early in the day, and check pots daily because they dry out fastest.
- Shade plants in the hottest hours, or move pots out of afternoon sun.
- Mulch the soil to keep roots cooler and moist.
- Hold off on feeding, spraying, pruning and repotting until the heat eases.
Keep it from coming back
- Choose heat-tolerant varieties for hot summers.
- Add organic matter to beds so the soil holds more water.
- Keep houseplants away from sun-baked windows in midsummer.
Read more
- Mulch basics
- How to protect plants in a heat wave
- Growing vegetables in containers
- Watering a vegetable garden
Sources
- University of Maryland Extension: Drought and excessive heat stress
- Missouri Botanical Garden: Scorch, sunburn and heat stress
- UC IPM: Heat injury to cole crops, lettuce and spinach
General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.