I've never experienced an instance of switching from 18/6 to 12/12, and then back to 18/6 producing any hermaphrodites. When I used to do it, though, I would revert back into a constant light (24/0) for about a week, then drop it back to 18/6 for as long as I felt was necessary. Not once did this ever produce a hermie for me, but that's not to say that it can't happen...so use your best judgment.

But, if you're really concerned with using this method to determine sex in your plants, then you can always just take a mature cutting from each plant, place it under a 12/12 regimen away from the rest of your vegging plants, and find out that way. You can actually root the female clones and veg them for a while, and flower them when the rest of the plants are ready...giving you some extra buds in the end.
Mr. Clandestine Reviewed by Mr. Clandestine on . Is Pre-flowering comming to soon? My plant is in the pre-flowering stage, but I want my plant to grow bigger before it flowers. Can I keep the lights at 18/6, let it grow for 30 more days then switch to 12/12? Or do I have to let it flower now? Rating: 5