So how dark must my room be so I don't have problems. I'm growing femanized seeds, soil, Humboldt nutrients, greenhouse grow and have to move to dark room, can I just cover or is it worth the time to move to complete dark room? My plants are tall already.
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Well, people say "the full moon is pretty bright," but it isn't, really. And most nights there is even less light.
When setting up a grow room, I wouldn't aim for "pretty dark," I'd try for DARK. Not just because of the chance that the screwy not-quite-dark environment will produce more hermaphrodites, but also because I'm not a fan of leafy bud. Also, because I tend to use the 40:60 rule for determining harvest dates and screwing up the cycle screws that up, too.
noun: dark; noun: the dark; plural noun: darks 1.
the absence of light in a place.
In terms of how dark should the "night" cycle be... Well, you cannot go wrong with "darker than six inches up a well-digger's arse at midnight" (although why he would be plying his trade in the middle of the night always escaped me, lol).