Well, I must admit that this is news to me too. All these years I understood that it was the phytochrome pigment as the primary agent of flowering trigger in cannabis. In the case of cannabis, there are other factors that can affect, typically delay, the onset of the photoperiod response. These include: the specific genotype, the age of the plant [the propensity of senescence hormones], of course the sex [early for males....see, even plants have early ejaculation issues], and any environmental stress. But like I said, I have always understood the phytochrome to be the primary agent. I think the existence of a specific 'florigen' is still a matter of general hypothesis, I would suspect that it is more likely a critical ratio of other plant growth hormones, such as Gibberellins and Anthesins, that set the stage for flowering, that is then triggered by the phytochrome agent.
So my curiosity is really up now, if not the phytochrome response, then what is the main trigger for flowering in cannabis?
You are correct that flowering does start well before the equinox, albeit rather weakly.
Perhaps it is an even more complex interaction between a broader set of hormones.
