I realize that this thread is pretty old but hopefully someone stumbles across this.
I read somewhere before that a way to tell if a seed is male or female is after they have germinated.
Apparently, if the sprout comes out of the top or bottom of the seed, it is a FEMALE.
If the sprout comes out of either side of the seed, it is a MALE.
I recently tried this out and I can confirm that it works. I germinated 5 seeds. 2 of them that I planted where sprouted out of the side (male) and the other 3 sprouted out of the top/bottom (female). Out of the 2 seeds that were potentially Male plants, 1 of them has shown sex and it is indeed a male. The other plant hasn't shown sex yet.
Out of the other 3 plants that were potentially female, all 3 have shown sex and guess what, all 3 are Females!!!
Having said that, this could all be a big coincidence. However, if this turns out to be a fact, then the world of growing has made a huge step forward!
Any inputs would be greatly appreciated!!!