You'll prolly scream once you read this, like why send me on a reading scavenger hunt and then say this, but here goes...lol. for me personally, after reading everyone's advice and techniques I ended up settling on one key signal that my plants are done. All I do is watch the pistils and the calyx. When the calyx swallow up the pistils, you'll see the plant practically stop taking up water and notice the buds really got fat on you. The weight and density come from the calyx swell ! By the time this happens, the plant is good and mature, with a nice ratio of Amber to Cloudy buds. I've harvested more than one plant before it's time, and this is what works best for me. Once this happens, there isn't much left for the plant to do besides grow seeds if it's pollinated. THC production halts and pre-existing THC begins to degrade into CBD on so on.
Did you know, the reason the Calyx envelops the pistil? In nature, when pollinated, the pistil grabs hold of the pollen, the calyx "swallows" the pistil, and then together they grow a seed ? Amazing ehh ? As I understand it, the delicious resin and THC we all love and adore is a wonderful consequence of the female plants desperate attempt to reproduce.
You'll have a much higher success ratio if you give your girls a 2 week head start
