^ This. UV is proven to have an effect on trichome/cannabinoid production, which is often overlooked by indoor growers. I remember years ago speaking to an industrial hemp grower who was having problems with local regulators, as the Industrial Hemp Act at the time stipulated a THC cutoff point of 0.5% for all hemp production - over that level, and it was was considered a drug cultivar. The problem was that the grower had sourced his hemp seed stock from China, where it had tested around 0.2-0.3% THC. However, as soon as he started growing it in Australia, where UV levels where higher, the same seed stock started to test 0.6-0.8% and higher. This was explained to the government authorities - that THC levels vary in hemp in relation to environmental conditions - and the solution was to mandate 0.5% seed-stock but no higher than 1.0% final production cutoff to recognise environment conditions outside a grower's control.
This is now all in official guidelines here:
https://www.foodstandards.gov.au/code/applications/documents/A1039_SD5.pdf
If anyone ever wants to argue UV does not affect cannabinoid production, go talk to a hemp farmer.
