From interviews and summaries, these are key points attributed to Dr. Bruce Bugbee about pre-harvest darkness vs extended light:
1. Cannabinoid/terpene synthesis needs light (energy input).
Without light, the plant cannot produce new sugars (via photosynthesis), which are the raw materials for making terpenes and cannabinoids. During dark periods, the plant may instead consume stored energy.
“No lights = no new energy = plants are not synthesizing new terpenes and trichomes in the dark.”
2. Extended darkness may consume reserves.
Because the plant continues metabolic activity even in darkness (respiration, maintenance), a long dark period could deplete stored carbohydrates and limit what’s left for final synthesis.
3. Bugbee favors keeping synthesis going until harvest, rather than “protecting” existing compounds.
One summary:
“We ought to put more emphasis on continued synthesis of terpenes right ‘till the last day of harvest, and less emphasis on doing something to preserve what’s already there.”
4. Bugbee is skeptical of the benefit of 24-72 h dark before harvest.
Some growers quote him as saying the practice is “bro science” (i.e. anecdotal, not evidence-based).
5. He suggests the “opposite extreme” could be 48 h of light, perhaps at lower intensity, rather than darkness, to maximize last-minute synthesis.
That is, if one wants to try something at the end, continuous light (or extended light) might make more sense than darkness.
6. Temperature plays a role.
Lower temperatures reduce volatility of terpenes (less loss via evaporation) but also slow synthesis. Bugbee seems to caution that observed benefits from “darkness” might actually be due to lower temperature, not the dark period itself.
7. No clear advantage has been demonstrated.
Some accounts state that Bugbee (or USU studies) have seen no clear advantage to a dark period before harvest in terms of cannabinoid/terpene content.
Bigup, keep grwoing and be nice. 💚🙏