In regards to doing anything special when you switch to 12/12...... there is a debate about giving them 24-36 hours of darkness when you make the switch to "kick" them into the flower cycle. I don't do that ...... I switch to 12/12 straight away.

This grow though I read the below on these boards and did exactly what is suggested, and the result have been superb.

I use grow big the first 2-3 weeks of 12/12,if you switch immediately to a high phosphorous fert you have a good chance of nitrogen defeciency at 30 days.The most agressive vegetative growth occurs during the "stretch" period of 12/12,mostly nitrogen should be given during this time.Cuttings lack phosphorous so what I like to do is give my donor plant a shot of tiger bloom several hours or the night before I take cuts,then I go 12/12 and continue with the grow big for 2-3 before switching to tiger bloom.I've used grow big in veg for several years,recently I found PBP veg to be even more effective.I use PBP for veg, grow big for the stretch of 12/12,and tiger bloom to flower

Hope this helps.

The items mentioned above are made by Fox Farms Ferts.

Hope this helps.