Usually I think these plants are grown from cuttings of already matured plants. I have three pistachio seedlings in my yard right now and am hoping to find in a few years that they are a mix of male and female. If that isn't the case I will order one tree of the missing gender from a nursery. That tree will have been produced from a cutting.
You have to be odd to be #1 - Seuss. An odd little ad: