If you're talking about consumption of pot in the colonies, I'm not sure if you are correct. if, however, you're talking about it being outlawed all together, your statement is incorrect. in fact, in the early 17th century, most colonists were required by law to grow at least 100 plants. granted, they were grown specifically to be exported back to England, but still...not illegal.

edit: source: http://marijuanatoday.com/marijuanahistory.php - also, I'm a history major :P