I have a few 1920s articles about growing hemp. They cover how the % of males to females can be skewed. These early scientists were trying to promote male flower growth, since the male produces hemp fiber, but their findings can be used for producing female plants.

CARBOHYDRATE-NITROGEN RATIOS WITH RESPECT TO THE SEXUAL EXPRESSION OF HEMP

(from the article) "10. An abundance of nitrogen at the time of fruit bud differentiation obviously leads to the production of female flowers, while the absence of nitrogen at that time tends to the production of male flowers."

Another one- Science/AAAS | Table of Contents: 26 September 1919; 50 (1291)

Enjoy!- Granny:hippy: