Most plants begin to suffer heat damage at approximately:

Most plants begin to suffer heat damage at approximately:

• A. 72°F
• B. 86°F
• C. 60°F
• D. 100°F

Answer: (B)

Most garden plants start to show heat stress when leaf temperatures reach the mid-80s Fahrenheit. About 86°F is the point where enzymatic activity and membrane stability begin to be challenged, so photosynthesis slows while respiration continues, leading to symptoms like wilting, leaf scorch, and stunted growth. That’s why 86°F is the best general estimate for when heat damage begins for many common plants. Lower temperatures like 72°F or 60°F are well within comfortable ranges for growth, while 100°F represents an extreme level of heat where severe damage is more likely, not the typical onset for most plants.

Most garden plants start to show heat stress when leaf temperatures reach the mid-80s Fahrenheit. About 86°F is the point where enzymatic activity and membrane stability begin to be challenged, so photosynthesis slows while respiration continues, leading to symptoms like wilting, leaf scorch, and stunted growth. That’s why 86°F is the best general estimate for when heat damage begins for many common plants. Lower temperatures like 72°F or 60°F are well within comfortable ranges for growth, while 100°F represents an extreme level of heat where severe damage is more likely, not the typical onset for most plants.