Because of his multiracial ethnicity and the government's apartheid policies, Hartze's playing options were limited. The
National Football League was white-only. Officials in Durban once tried to change his registry designation to white so that he could play in the NFL but were unsuccessful. After a time at Berea F.C., he joined
Orlando Pirates in late 1967 This left the
Federation Professional League, a league comprising coloureds and
Indian South Africans, as his only professional option. In 1970, he served as a
player-coach for
Cape Town Spurs F.C. and depending on which source material is referenced, Hartze won scoring titles while at Spurs in 1970, 1971 and possibly 1972. It is reported that in 1970 he scored 54 goals in 30 games and earned South Africa's Sportsman of the Year award. Another source has him scoring at an even more torrid pace in 1972: 35 goals in 16 matches. There is also a report of him scoring both goals in a cup final for Cape Town United as they overcame his former club Spurs, 2–0. In December 1974 he was the third player to sign with the newly-formed
Tampa Bay Rowdies of the
North American Soccer League, He played on loan for Cape Town in 1975-76 during the NASL's off-season before returning to the U.S. in 1976. That spring Hartze joined the
Tacoma Tides of the
American Soccer League on loan from the Rowdies. He was then traded to the
Sacramento Spirits in June 1976. In late July after the firing of head coach Dick Ott, he was named player-coach with eight games remaining in the season, guiding the Spirits to a 3–1–4 record. As South African teams began integrating, he returned home in 1977 and signed with NPSL side
Hellenic F.C. The following year the NPSL was reorganized to officially become non-racial. ==Coaching==