I usually give mine 24 hours before harvest

I always do this now. With both phenotypes of Ice, they start showing hairs about 5 or 6 days quicker, and finish 5 or 6 days quicker. I have just switched them to 12/12 and let them go, but it takes longer and doesnt yeild any more for me. Why not do 36 hours darkness to get them going. I have never had a hermie or less yeild from this. I learned of this by accident when a wind storm knocked out power for 3 days. Had yeilds that was the same as the last 4 or 5 grows, just quicker. I suppose it could give some strains some problems...not sure. I do believe I read somewhere(serious seeds website ???) that they recommend 36 hours darkness at the onset of flower.

I asked the same thing as I read it in a book...here is the quote

Give plants 36 hours of total darkness just before inducing flowering with the 12/12 photoperiod. This heavy dose of darkness sends plants an unmistakable signal to flower sooner. Growers using this technique report that plants normally show signs of flowering such as pistil formations, within two wWeeks and develop pistils after a week of flowering.
Growers have experimented with giving plants upto 48 hours of total darkness to jump-start flowering and have found that 36 hours three contiguous 12-hour nights-is most effective.


my post (incase you want to read through the comments)
General consensus? 36hrs of dark before flower?

Well, we did this and now going into the 3rd week of flower (monday)...it is my first grow so cant compare it. BUT i can see lots of bud sites with shit loads of white hairs. I will try take some pics for you man...they look awesome