The ground effect on the wingtip vortex generated by a rectangular semi-wing equipped with tip-mounted regular and reverse half delta wings was investigated experimentally. The passive tip vortex control always led to a reduced lift-induced drag as the ground was approached. In close ground proximity, the presence of the co-rotating ground vortex added vorticity to the tip vortex while the counter-rotating secondary vortex negated its vorticity level. The interaction of the ground vortex and secondary vortex with the tip vortex and their impact on the lift-induced drag were discussed. Physical mechanisms responsible for the change in the vortex flow properties in ground effect were also provided.