Auto duck GreenHouse 2020

Keep eye on the trichomes, they turn amber

Depends on what you mean by potency. Highest THC content comes when about 70% of the hairs turn red and about 10% of trichomes turn amber. Strongest effects come when 90% of hairs are red and 20% of trichomes are amber. This is because THC starts breaking down into other cannabinoids eventually. These cannabinoids offer strong effects that add to the effects of the THC. While recreational smokers tend to prefer these amazing, intoxicating effects, medical users tend to prefer the higher THC content. 5-15 days depending on your personal preference.

Just watch the triclomes for ambering, if you havent got the means to do that then wait till most of your hairs have changed, then flush. Cheers friend