Barley is native to the temperate growing regions of the world. It does not grow well outside of the temperate zone, which means it is not typically grown commercially subtropical or tropical zones, nor in arctic or frigid zones. In the US, the major barley grown regions are Idaho, North Dakota and Montana, with lesser amounts grown in a number of other States. Great Western Malting sources a large portion of its supply from Idaho, with additional amounts from Washington, Oregon and Montana.