Sorry johnou85, this was not a pole of what photoperiod to use, or even a discussion of "normal" photoperiods. And btw, people need to "rest" plants don't.

Jung3Jim,

Besides a plant having an overall circadian rythym, the ability of a plant to go to flower or to stay in veg is determined by the photoperiod. Marijuanna is a "short day" plant but it is more accurate to say a "long night" plant since the plant measures the dark period. It does this by produceing chemicals (auxims) and hormones (floragen) during the dark period and sending them to the plants apex. These chemicals build up during the dark and are lost again during light. (This sounds famiilar, chk your thread "when does flowering start" of Oct 15th, '09).

The plant can build up these chemicals and go from induction to initiation of flowering in 24-36 hours of darkness. But will fall out of initiation or even the developemental stage of flowering if given light for 14-16 hours. So technically you can extend the overall day length, if you extend the dark period, but cannot extend the photoperiod. So you could theoretically create a "36 hour" day, but it would be 24hrs dark and 12 hrs of light. The results of that extended day would be less growth, due to certian processes taking longer to switch over on the light change and an increased risk of hermephodites due to the unnatural rythym.

This begs the question; why would you want to extend the "grow day"? Especially if it does not improve the final product or slows rather then speeds up flowering time. Time is money (re cost of electrical power) so trying to speed flowering up is what most people concentrate on trying to do, when screwing with the length of the grow day.

Hope that makes sence or cents to ya.:thumbsup: -oldmac