Gov. John Hickenlooper on Thursday issued an executive order telling state agencies that any marijuana grown with unapproved pesticides is a threat to public safety and should be removed from commerce and destroyed.

Colorado, already a national leader in hemp cultivation, is pushing forward with a plan to certify seed, in part to ensure THC levels, the active ingredient in marijuana, do not exceed legal levels.

The Colorado Department of Agriculture is working on the world's first government-produced manual on how to grow marijuana.

The Colorado Department of Agriculture is working on the world's first government-produced manual on how to grow marijuana.