I can try to find the source again - but basically all the colonists were required to grow hemp by decree because it was such a multipurpose plant. At that time, almost everyone was growing it for the fibers, and the fibers get tough when the plant goes to seed, so they chopped off the buds and flowers early and used them as animal feed to preserve the fibers. It also self seeds very easily - you might say it grows like a weed. Haha.