When you have a seed with just X chromosomes, you are certain this seed will grow into a plant that is genetically female. To achieve the XX only plant: a female plant is forced by a hormone called Gibberellic Acid to produce male flowers, the pollen created contains only X chromosomes, when you offer this pollen to another female plant you can be absolutely certain to get seeds which are 100% XX. Once again this seed is called FEMALE SEED. Gibberellic Acid can be found in online. It takes years for an individual to achieve the proper plant hormone manipulation to get 100% female XX seed. Supplies therefore fluctuate and there are many different strains available worldwide

Spray a branch with gibberalic acid and cover with a bag to collect the pollen. I would spray when a plant begins meiosis, i.e. budding. I have never used it but I hear all you got to do is spray it on.