when to sex and when to cull

just like the title says when is the earliest time to tell the sex of the plants. and when should you get rid of the males. I'm planting super skunk and white widow..

im actually also growing a skunk/widow cross...preflowers develop 6-8 weeks of life, they show sooner if you veg 18/6 rather than 24/0. You want to ditch the bastards asap to avoid any loose pollen contaminating your grow room. have pics? good luck.

you might be better than me. I had to put mine in the flowering time 12/12, for 14 days, before I could tell the sex.