Flowering Time

[PTSativa]

Sort of a novice question. I know when to harvest by looking at the trichs, but when a seed producer says a strain has an eight week or ten week flowering time for example does the eight or ten weeks technically begin the day the lights are switched to 12/12 or the day the farmer first sees flowering appear? Thank you very much in advance and best wishes for a happy Thanksgiving to all.

 

[Dunge]

12/12 light switch = start of flower clock

 

[Bannacis]

Technically it's at the 12/12 switch is when you start day count. The breeders statement of harvest is usually has a 7-10 day window, as cannabis has a 2 week flowering harvest window.
It is always a give and take on the harvest, even a strain that has been grow out over and over can have varying harvest times.
There's a few reasons that peeps have different harvest times from each other or their regular strain varies in harvest time.
That is when there is differences in techniques of growing, or some problems arise.
A grower can prune different, change watering schedule, diff nutes, weather/climate different, plant gets injured, Mess up on flushing, the water ph/ecc out of normal...etc...
All those things plus... can have affect on harvest.
That is why trichomes are always checked. Then on next grow you have a better idea, just take in the facts of how this grow is compared to last same strain grow. adjust your harvest time if needed.