So worth the effort to start with clones, specially when you are doing an outdoor grow. Indoors you can force flower to determine sex. Also as you gain experience you can get pretty good at telling before flowering starts. Read up on the difference of the pistols from boys and girls. Nothing worse the spending an entire season growing from seed to find out you have boys. The only option is to grow twice as many as you want, odds are 50/50 you'll get male/female. Don't waste your cash on feminized seeds either, they're not 100% female and they charge insane prices. Good Luck