Gartner initially played reserve grade for Canterbury occasionally being called up to the first grade side. Gartner played in the 1960 semi final loss against Eastern Suburbs. Gartner missed both the 1961 and 1962 seasons due to a shoulder injury. He returned to the first team in 1963 but missed the entire 1964 season due to a broken jaw. The 1964 season also finished for a wooden spoon as the club finished last.
Gartner made 21 appearances for Canterbury in 1967 as the club reached the grand final after years of struggling on the field. On their way to making the final, Canterbury defeated St George 12–11 at the Sydney Cricket Ground in the preliminary final ending St George's 11 year premiership reign.
Gartner played on the wing in the 1967 NSWRL grand final as Souths took an early lead. Canterbury then regained the lead to be ahead 8-5 until Canterbury hooker Col Brown tried a looping pass which was intended to find fullback Les Johns only for Souths player Bob McCarthy to intercept the ball and race away to score a try. Souths then went on to kick a late goal to win the match 12–10. Gartner played one final season for Canterbury in 1968 before retiring. In total, Gartner made 152 appearances for Canterbury across all grades.[2][3][4][5]