pre-sexing

I either read or heard somewhere that there are signs to tell on a plant at about five weeks if its male or female. Is this true or was I stoned and made it up in my mind?? Here is the link to the whole grow and all its problems. Right now it is on 30 minutes of ph'd to 6 water with half the recomended nutes. https://www.rollitup.org/marijuana-plant-problems/31111-what-hell-did-i-do.html

Yes its true....Most plants will show pre-flowers after a few weeks before going to 12/12.

The faqs has info on it.

Thanks man appreciate it