Actually, Washington's diaries talk about his hemp crop, and include this passage:
"Began to separate the Male from the Female hemp â¦ rather too late."
The only reason to separate the male and female plants is to prevent pollination, and thereby increase (psychoactive) resin production. This is still done to this day among pot growers. It seems pretty clear that Washington had at least some interest in the medicinal/psychoactive qualities of his crop.