Josephine Sanford was born April 14, 1927, in Britt, Iowa. Her father Ward and her mother Kathleen raised her and her two brothers in various communities in western Iowa where Ward Sanford taught high school physical education. Kathleen Sanford was from Ruthven, Iowa, and Josephine attended Ruthven High School, graduating in 1945. Despite her dislike for school, she followed her parents' encouragement and pursued a two-year teaching course and then enrolled at Morningside College, where she graduated in 1951.

During and after her college years, Josephine Sanford taught rural school. She reported that "it was typical for the young bachelor farmers to check out the new school marm" and that is how she met future husband, farmer Don Gruhn. After marrying, they lived in their own home at his parents' farm near Spirit Lake and she taught school for one year. After her first child was born, she was a substitute teacher for twenty-eight years.

During that time, she was an active member of a variety of civic organizations and the Democratic Party. Donald Gruhn resigned his seat on the the Democratic Central Committee in Emmet County when he was appointed to the Agricultural Conservation Board and Josephine Gruhn took that seat. In 1982, redistricting created a new seat in the Iowa House of Representatives for Emmet and Dickinson Counties. The Democratic Central Committee asked Josephine Gruhn, now a widow, to run for this seat on an education platform. With the help of her colleague, second grade teacher Stephanie Heitman, they ran an effective and innovative campaign resulting in her election in 1982.

As a member of the Iowa House of Representatives, Gruhn was vice chair of the Committee on Agriculture during the farm crisis of the 1980s. She was a moderate Democrat, responding primarily to her constituents' concerns--roads, schools, and relief for the agriculture sector. She served four consecutive terms as representative from District 12, from 1982 until retiring in 1992. Josephine Gruhn passed away in 2015.