You NEVER flush a soil grow for more than 2 weeks tops-- more- and you not only starve the plant, but lose a HUGE amount of yiled, slow bud & resin production, and CAN often end up harvesting early... how can you tell 3 weeks ahead when it will be ready?
You do NOT EVER harvest just because it saysd 60 dys to harvest and it has been in 12/12 60 days-- MANY plants go longer than the breeders estimate.
Timing when the trichomes will be ready and still have a 2 week window to flush is difficult at best...
That , and the fact that the plants put on the most bud size/weight and raise the thc/resin production the last 2 weeks of "productive" bloom is why I ALLWAYS suggest the Emergency flush.
You wait until they are ready to chop--- then flush for 3 days in 12/12 and then harvest.
Flushing means getting all nutrients away from the roots of the plant -- that forces the plant to use all the nutrients allready stored in her system (including the roots!) to produce more resins, sugars and THC.....
Harvesting, Drying & Curing: http://www.marijuanagrowing.eu/cannabis29259.html
Flushing, trimming Curing: http://www.marijuanagrowing.eu/sutra332630.html#332630
Bubbler Flushing tutorial: http://www.marijuanagrowing.eu/cannabis29346.html
How to tell When to Harvest: http://www.marijuanagrowing.eu/cannabis6774.html
Photos for When to Harvest http://www.marijuanagrowing.eu/cannabis2583.html