he's 100% right. but once you see them get it out!!!!!! (if your lookin for sensi)if it is a male, you'll have plenty of time to spot it before it drops its load on the females..
You can but it will likely cause minor stress. In the future just veg until they show preflowers, usually 5-7 weeks of age. No need to put into 12/12 just to determine sex. Also taking clones from a vegging plant to check sex is effective.So here's a question.. After being on 12/12 to determine sex, is it possible to go back to 18/6 or should I keep it at 12/12 for the duration?