quelle fréquence PPDF en mode croissance

It depends of air flow, leaf temperature and air temperature in combo with relative humidity and co2 levels. One thing i learned from my experience is that we often go too gentle with them so i think that you are hitting the hot spot if your other environmental factors are aligned with it. DLI is also good to consider in every phase of growth

Daily Light Integral - read the wiki. Get the gist of it. PPFD and hours of operation are required to understand how much light you are providing. One without the other is half the information necessary. Simply Reference a DLI table. Important to note, no matter what you choose as your initial DLI target, you will most likley still have to observe and adjust from there. It'll get you close, but your local Temperature, RH and atmospheric CO2 will dictate how much DLI you can give without damaging the plant. If too tight, needs less. If too lanky, needs more. Interveinal damage (initially and gets worse)) on leaves is another sign of too much. Too much will stunt a plant and it can take a week or two to resume proper growth in extreme cases. The plant and local variables dictate how much you can give... The suggested 35-40 dli stuff out there is just getting you into the ballpark for smaller required adjustments. If oyu calculate based on total power oflight, shoot for 40DLI. if using some free app to measure PPF at canopy and calculating DLI from that, shoot for 35. The latter takes some competency at measuing multiple locations and properly calculating an average over entire canopy. PPFD is not a single-point measurement.

I think its better to use DLI vs PPFD its a more rounded out calculation t how much a plant is getting. EG. 600PPFD at 12hrs vs 20hrs are wildly different. eg 12hr=25.92 DLI vs 20hr=43.20 DLI https://www.waveformlighting.com/horticulture/daily-light-integral-dli-calculator https://en.wikipedia.org/wiki/Daily_light_integral Plants can use over 40DLI unless some things are boosted and locked in. I grow aorund 35-37DLI for buffer.

460ppfd # Seconds in 18 hours = 60x60x18 = 64800 seconds 6480 seconds x 460ppfd = 29,808,000µmol @18hours @460ppfd =29,808,000µmol or 29.8mole or 29.8DLI @18hours @600ppfd =38,880,000µmol or 38.9mole or 38.9DLI IF you're doing 18 hours, I'd recommend 600.