Troubleshooting Hydroponic Snow Peas in High Heat

Snow peas thriving in an auto-pot hydroponic system suddenly declined during a week of 30°C+ temperatures in Victoria, Australia. Heat stress is a prime suspect, but root issues and pests can mimic heat damage.

Heat Impact on Peas

Peas prefer cool weather (10–20°C). Sustained high temperatures cause flower drop, poor pod set, and leaf yellowing. In hydroponics, heat also reduces oxygen in the nutrient solution, stressing roots.

Diagnostic Checklist

• Root health: Sacrifice one plant—cut near the crown and check for dark brown/black roots (indicating root rot).
• Uniformity: Are all plants affected? If yes, environmental (heat) is likely. If patchy, check for pests or irrigation issues.
• Pests: Inspect leaf undersides for spider mites (tiny, 1–2 mm, with webbing on petioles)—they explode in hot, dry conditions.
• Nutrient solution: Ensure proper EC/pH, temperature (<25°C), and oxygenation.

Immediate Actions

1. Cool the root zone: shade reservoirs, add chillers, or run circulation at night.
2. Increase humidity and airflow around foliage.
3. Apply predatory mites or insecticidal soap if spider mites are found.
4. Consider a heat-tolerant pea variety for future crops.