IR Licht in der Blütephase

6 hours a day from week 3 of flowering until week 7 of flowering was the answer I got from my research a few years ago.

https://youtu.be/IJCLxCZ5qrI

ePAR is what you want to look into.. bsically the early research was limited by technology at the time and the intiial range of PAR (photosythentically active radiation) is wider than they initially definied it. So, IR is a far red wavelength.. if its in the ePAR range (extended PAR) then it probably helps throughout the grow. I don't know what level of it is needed before there is diminishing results, but if it aids or improves photosynthesis taking place, then it's most likely good from start to finish anytime photosynthesis is taking place. UV is different. It is not doing anything fro photosynthesis and damages the plant. The hope is that a minimal amount of damage causes a healing response that increases trichomes, which seems to be a measurable effect, but also means that UV treatments in vege phase are useless. So, don't confuse that reasoning with any of the wavelengths of radiations that are photosynthetically active. Bruce bugbee has done some more recent research on ePAR. Good idea to look up his findings and ignore the shit you read in grow questions and forums becvause those people are not PhDs on relevant topics, and neither am i. This isn't something you can truly understand with a high school education or even 95% of 4-year degrees for that matter.. it's specialized knolwedge that only certain people need in their professional lives. Same reason i don't know how to rebuild a muffler, lol. We trust others with experience and education on the topics we cannot resolve with a glance or a smell.