What PPFD measures
PPFD describes the number of photosynthetically active photons landing on a square meter each second. It is useful because it focuses on light that actually reaches the canopy instead of the light leaving a fixture.
Why canopy position matters
The center of a bench, the edge of a tray, and lower leaves can all receive different photon densities. Measuring a grid reveals hot spots, shadowed zones, and spacing problems.
How teams use PPFD
Production teams tune recipes by crop stage. Seedlings may need gentle light, while later stages can support more photons when climate, irrigation, and nutrition are balanced.
Measurement discipline
Good PPFD practice records fixture output, mounting height, sensor angle, time, and canopy condition. Repeating the method makes comparisons trustworthy.