When growing cannabis, does the dark in the light-dark cycle need to be absoultely pitch dark, or would dark ish be ok too?

I read somewhere that any light at all during its rest time will fck with the plant in undesirable ways, but I'm kinda skeptical about that.

What you got to tell me about this?

If I have them under lights 18 hours , and 6 hours in a dark-ish room, is that ok too?

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Dolimyte · 41-45, M

Not a big deal in vegetative growth stage. Flowering is a different story. I had three plants in my tent, there was a small light leak that I didn't notice right away. The one closest to the leak didn't flower but the other two did. Absolute pitch black is not required, but there is a point that's too much. Led indicators on powerbars or fans generally aren't a problem. If light is an issue, grow auto flower.