08/30/2026
What does heat stress do to zinnias?
Sustained temperatures above 90°F cause heat stress in zinnias, leading to wilting, leaf scorching, flower drop, and reduced plant vigor.
Signs of Heat Stress-
Wilting: Leaves and stems droop during the hottest part of the day as water evaporates quickly.
Leaf Curl and Scorching: Leaves turn brown at the edges or curl up to protect themselves from moisture loss.
Flower Drop: Plants drop existing blooms or stop producing new flowers entirely.
Stunted Growth: Overall plant vigor drops, and any new flowers that manage to grow may turn out very small.
Irreversible Damage: Temperatures passing 100°F can kill the plant or cause permanent tissue damage.
