you do not have to go to 12/12 to determine sex as they will show preflowers on an 18/6 light cycle by the time they reach a certain age wich can vary but is usually somewhere between 3 - 7 weeks old.
if you must go back to 18/6 would probably do it now or you could also take clones now and continue to flower the plants and start the clones under 18/6
bejay Reviewed by bejay on . HELP - From 18/6 to 12/12 to 18/6 (light cycle question - clone) I switched to 12/12 light cycle 4 days ago and I can already see some males and some females. I have 2 questions for you: 1 â?? How long should I leave them in a 12/12 environment before I can be 100% sure I do not have hermies and can be sure they are male or female ? 2 â?? After I only have females, how long should I wait before I can clone my female after putting them back in an 18/6 light cycle ? Thanks, 9KtuFK Rating: 5