Plant-Science Foundations

Why cannabis yield rises almost linearly with light far past where a single leaf saturates, and the four terms — PAR, PPFD, DLI, µmol/J — every commercial decision runs on.

Stage-by-stage PPFD and DLI setpoints, the 800–900 PPFD ceiling without CO2, and why fixture efficacy beats spectral tweaks for ROI.

What VPD really is, why it — not RH — drives transpiration, and the stage-by-stage kPa targets that steer the crop.

Why leaf temp runs cooler than air, how that changes real VPD, and the crop-steering logic that ties VPD × leaf temp × light to nutrient uptake — with an SOP for a daily VPD check.

Why cannabis is CO2-limited at ambient, the 1,000–1,500 ppm target, the ~1,200 ppm sweet spot, and the hard rule that CO2 only pays above ~800–900 PPFD.

How light, VPD, leaf temp, and CO2 interlock into a single throttle — the master setpoint table and the sequence to raise them without breaking the plant.