Darkness before harvest means switching the lights off, or covering outdoor plants, for 24-72 hours before the chop. Proponents say the stress makes the plant pump out more resin or THC. There is no credible evidence that it does.
In practice
GenetixBay's advice is simple: keep the normal light schedule right up to harvest, and cut when the trichomes say so. If a dark period helps with logistics (planning a lights-off harvest day, for example), treat it as logistics, not quality.
Why it makes no sense physiologically: - the last weeks are when the plant packs on most of its final weight and resin; - trichome resin is built from photosynthesis, so switching it off takes away the supply; - a day or two of darkness can't build meaningful new gland mass; - lab-measured cannabinoid increases from short dark periods haven't held up in controlled work.
Don't confuse with
- The flowering dark period: the nightly 11-12 h dark that triggers and maintains flower.
- Light deprivation: covering outdoor plants to force early flowering.
- Harvest window: the right time to cut, judged by trichomes.
Myth check
Myth, "complete and utter nonsense" in the founder's words. Why cut photosynthesis in the most critical part of the life cycle? The founder's standing challenge, open for 20+ years: find a peer-reviewed study (not a single-plant study, not biased or skewed) showing a benefit, and a 50-pack of seeds is yours, no questions asked. Nobody has claimed it. See Mythbusters.
