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>From _Licit & Illicit Drugs_, by Consumer Reports, p. 403:

...In 1762, "Virginia awarded bounties for hempculture and
manufacture, and imposed penalties upon those who did not
produse it." 

George Washington was growing hemp at Mount Vernon three years 
later--presumably for its fiber, though it has been argued that
Washington was also concerned to increase the medicinal or
intoxicating potency of his marijuana plants.*

The asterisk footnote:
* The argument depends on a curious tradition, which may
or may not be sound, that the quality or quantity of marijuana
resin (hashish) is enhanced if the male and female plants are 
separated *before* the females are pollinated.  There can be no
doubt that Washington separated the males and the females.  Two
entries in his diary supply the evidence:

	May 12-13 1765: "Sowed Hemp at Muddy hole by Swamp."
	August 7, 1765: "--began to seperate (sic) the Male from
	the Female Hemp at Do--rather too late." 

George Andrews has argued, in _The Book of Grass: An Anthology of 
Indian Hemp_ (1967), that Washington's August 7 diary entry
"clearly indiactes that he was cultivating the plant for medicinal
purposes as well for its fiber." [7]  He might have 
separated the males from the females to get better fiber, Andrew
concedes--but his phrase "rather too late" suggests that he 
wanted to complete the separation *before the female plants were
fertilized*--and this was a practice related to drug potency
rather that to fiber culture.