cobshopgrow, thanks for posting the spectrometer reading from your windowsill sunlight. Thanks for letting us all discuss these interesting things here. So many posts, too many to like.
Grotbags, Rocket and others have brought up points. I might be reading more into comments and observations because of personal slant or bent.
I feel that lighting intensity, temps, humidity work together like some weird hybrid between a playground seesaw and merry-go-round. If the balance between elements are somehow out of wack, the thing won't spin as smoothly.
We can see beautiful examples of
vegging under a variety of lights. Something that stands out, is plants appearing lush hues of green. 5K -3K, and even blurple. Some with very low intensity levels, we also tend to see larger fan leaves on the plants.
But flowering is a much more intense use case. The plant system is working in a different mode, levels of hormone are different. The calls on the plant system are different. We can up the lighting intensity levels, but that does not drive photosynthesis at peak in isolation. Everything else has to be in balance.
I think we underestimate spectrum. But I think we make it a scapegoat for other factors. People basically only knew HPS for years, and look at what a crap spectrum that was. As for sunlight, cobshopgrow has posted the spectrum a few posts above. Naturally flowering outdoors, the level of reds does increase in ratio overall for a 12 hour day compared to summer solstice as the weeks go by . But it is nowhere as dramatic as you will see if you go compare examples from Fluence and Gavita compared to the HLG 550R and 650R.
https://growershouse.com/blog/led-grow-light-ultimate-comparison-review-using-light-laboratory-data/
I might be imagining it, but think someone posted, suggesting that we should be revisting light intensity levels. I would agree. Shoot me. But line your ducks up first. VPD temps/humidity, co2, etc. I don't see how we can blame our tools when there are others out there using the same ones.
