The yield numbers come from a real trial: Rodriguez-Morrison et al. (2021) grew 384 cannabis plants at canopy light levels from 120 to 1,800 µmol/m²/s. The headline finding surprises people — yield rose in a straight line the whole way, with no plateau. Twice the light, near enough twice the bud, right up to the highest level they tested.

So why do the stage bands above stop calling it "ideal" past ~1,000? Because the ceiling isn't the plant — it's everything around the plant. Push PPFD up and she needs more water, more nutrients, more airflow and ideally added CO₂ to use it. Run her hot and hungry under a big light and you'll bottleneck somewhere else and blame the light. The bands are about what most home tents can actually feed, not the plant's limit.

More light does not mean stronger bud. The same trial found THC and CBD percentages didn't move with light at all. You get more grams at the same strength — a bigger pile, not a stronger one.

The DLI (Daily Light Integral) is just your PPFD added up over a day's lighting hours. It's the honest way to compare setups on different photoperiods: 1,000 PPFD for 12 h and 750 PPFD for 16 h deliver almost the same daily light.

Honesty notes: the flower band is research-backed; the seedling and veg bands are conventional grower ranges, not from this paper. The yield figure is a flower-cycle estimate from the trial's regression (Y = 0.0122·PPFD + 33.8, R²=0.59) — a fair guide, not a promise; your genetics, training and feed move it. The fixture-estimate mode is exactly that — an estimate; a €15 quantum sensor pays for itself. Source: Rodriguez-Morrison, Llewellyn & Zheng (2021), Frontiers in Plant Science, doi.org/10.3389/fpls.2021.725078 (open access).