Circumstantial evidence for UV in flowering

Hey wavelength fanatics, I posted the question whether to move some indoor plants that really should be finishing and showing amber trichomes by now to different sections; plant problems and subcools organics, since it may have also been related to supersoil, which i used in the grow. But y'all may find the result useful here.

These plants (under HPS) seemed really overdue to finish but no amber. I want ambering to enhance the balance towards body effect and reduce raciness in the 50/50 sativa/indica hybrid. I though maybe the plants were not receiving UV so wondered whether giving them some good old sunshine would do the trick.

Three days under the sun and BAM! Amber. Harvest time!

I'm interested in thoughts whether it was indeed the UV specifically or something else.

For LED heads, it's not specifically LED related, but I asked some related questions during my first grow. I harvested plant #1 yesterday and I posted a retrospective account of the grow here: https://www.rollitup.org/organics/692736-thanks-riu-people-great-first.html

Thanks to everyone who has answered my noob questions along the way. Hopefully by the time I start another grow indoors next year it will be with LED/and or induction lighting

Cheers!

UV led's are expensive as fuck and still don't cover the right uvb wavelengths. 310nm uvb florescent are the best for supplemental uvb. Aapche put a decent amount of research to use diodes for it and came to the conclusion that the floros are best and cheap.

As for UV in HPS/MH
There isn't very much being put out, but the glass in the reflector doesn't let any of the uv through, so if you want uv you need to take your glass out late in flower.

Or use some sun!

Starting to see just a few amber trichomes on the other 2 plants today.