Temperature Effects on Plant Growth: Heat, Cold, and Seed Germination

Weather profoundly affects plant growth. Frost damage is obvious, but extreme heat is equally harmful. Species vary widely in temperature tolerance—some wilt at moderate warmth, others thrive in extremes.

How Temperature Affects Growth

High temperatures increase both photosynthesis (CO₂ → O₂) and respiration (O₂ → CO₂). But beyond species-specific thresholds (e.g., tomatoes struggle above 96°F/36°C), these processes unbalance. Influencing factors: sunlight exposure, moisture drainage, elevation, day/night temperature differential, proximity to thermal mass (rocks).

Temperature and Seed Germination

Germination rises with temperature to an optimum, then declines. Cool-season vegetables (lettuce, broccoli): 55-70°F (13-21°C). Warm-season plants (squash, marigolds): 70-85°F (21-29°C).

Check plant hardiness zones for compatibility, but remember—weather remains beyond our control even in optimal conditions.