Quote Originally Posted by NeverEnough
I didnt follow the link the guy posted but the difference is that during the period of night allows the roots to grow. Without the darkness the roots will not grow as well.
Sorry NeverEnough but you are mistaken. Roots DO NOT grow during the dark period, only during the photoperiod. While the roots my grow below ground level in darkeness unless the part of the plant above ground level is in photoperiod (has light) no growth occurs.

That is why when rooting cuttings the most suggested method involves 24hrs of fluroescent (much blue, low intensity) light. If plants needed dark at this stage of growth to grow roots, the 24hr method would not work at all.

I hope this helps clear up your confusion.

BTW, there is some debate as to whether the plant needs a dark period during vegative growth stage, there is no science to indicate that either.