In Hartwig's first collegiate season in 2020, he played in six games while making three starts en route to being named a Big Ten honorable mention.[4] During the 2021 season, Hartwig played in and started all 13 games for the Boilermakers.[5][6] Heading into the 2022 season, Hartwig was named to the Rimington Trophy watch list which is awarded to the nation's top center.[7] In the 2022 season, Hartwig would play in and start 11 games for the Boilermakers before suffering an injury.[8][9] During the 2023 season, Hartwig played in and started nine games after missing the first three due to an injury from 2022. For his performance in the 2023 season, Hartwig would once again be named Big Ten honorable mention.[10][11]