In 49 states (and four Canadian provinces) where the program exists, Master Gardeners (MG) are trained and supervised by the Cooperative Extension Service (CES). In fact, the CES created the MG Program. When you work as an MG, you are representing the CES in your state. enesis of CES The CES grew out of the U.S. Congress’ concern for the education of the average citizen. Prior to the Civil Wa…