ppfd is a flawed way to compare lights.
Extreme red photons (700 nm) have only 4/7 as much energy apiece as extreme violet photons (400 nm).
A red LED having the same ppfd as a violet LED will only emit 4/7 as much power as the violet LED.
When comparing 2 lights, only if they have close to the same spectrum, will ppfd offer an accurate comparison.
A better way to compare lights in my opinion is to specify how close they come to the sun's spectrum, along with actual light power emitted.
I'd guess that a lower power light that matches the sun's spectrum would out-perform a slightly higher power light that doesn't.
I agree that PPFD may be flawed, but it is a pretty good indicator of where you're at, intensity wise. Also, it feels like a pretty big step taken in the right direction switching out LUX for PPFD.
As long as your spectrum isn't made of mostly 400nm or 700nm light, and instead is a pretty "normal" spectrum where most of the power is spread somewhat evenly between 415nm and 685nm, I'd say that PPFD gives us a pretty good picture. Even between different lights and spectrums. Other than that, most of the serious grow light brands today displays PPFD-maps for their lights, which I think makes a good DLI-chart even more useful. For now, it is the best and most widely used "standard" that we have.
This blog post and chart is for tuning in your distance between plant canopy and lamp, together with photoperiod. It was created especially for the ones asking questions like "How many lumens do I need and what is kelvin?". Both for people growing cannabis, as well as people that grow tomatoes, peppers, or herbs.
There are numerous DLI-calculators out there where you type in your PPFD and photoperiod to get a DLI value. I think that a chart, pre-made with all options, gives a better overview of the relationship between intensity and duration for people with little experience.
Do you have any thoughts or ideas of how it could be improved? I'd love to hear what you think
