Visual reference slot
Needed asset: Stomata Open/Closed Diagram showing guard cells, pore, CO2 entry, water vapor exit, and VPD pressure.
Field checklist
- Check leaf posture and edge curl during hot or dry periods.
- Inspect underside when pest pressure is possible.
- Compare symptoms before and after lights-on peak.
Measurements to pair
- Air temperature, RH, VPD, leaf temperature.
- PPFD/DLI and airflow direction.
- Substrate moisture and irrigation timing.
Common mistakes
- Treating VPD as a single perfect number.
- Ignoring leaf temperature.
- Assuming stomatal stress is nutrient burn.
Grow Doc prompt
Check stomatal stress signals: VPD, leaf temperature, RH, airflow, water status, light intensity, edge curl, and time-of-day pattern.