This Jan. 26, 2013 photo taken at a grow house in Denver shows a marijuana plants ready to be harvested. Last fall, voters made Washington and Colorado the first states to pass laws legalizing the recreational use of marijuana and setting up systems of state-licensed growers, processors and retail stores where adults over 21 can walk in and buy up to an ounce of heavily taxed cannabis. Both states are working to develop rules for the emerging recreational pot industry, with sales set to begin later this year.(AP Photo/Ed Andrieski)