Fertile is a city in Polk County, Minnesota, United States. It is part of the Grand Forks ND-MN Metropolitan Statistical Area. The population was 842 at the 2010 census.The annual Polk County Fair is held in Fertile and dates back to 1900. The Polk County Fair is also the main attraction for the town of Fertile during the summer. It holds many competitions for crops, animals, and man made items.