In this photo taken on Saturday, Feb. 9, 2013, Mark Poullin looks at chemicals for use on plants as they are passed around the classroom at THC University in the Tivoli in Denver. Marij

 

              In this photo taken on Saturday, Feb. 9, 2013, Mark Poullin looks at chemicals for use on plants as they are passed around the classroom at THC University in the Tivoli in Denver. Marij
In this photo taken on Saturday, Feb. 9, 2013, Mark Poullin looks at chemicals for use on plants as they are passed around the classroom at THC University in the Tivoli in Denver. Marijuana classes are popping up in Colorado as people seek help growing their own pot. (AP Photo/Ed Andrieski)