Following his injury, Groener took a position as a fitness coach for
FC Twente. From 1974 to 1978 he was the manager of
Quick '20. In 1978 Groener finished his studies to become a A-level certified football coach, taking the managerial position of the
Suriname national team. He successfully lead the country to its first
CFU Championship in 1978. In 1979, he returned to the Netherlands taking a job as manager of Quick '20 once more. In June 1981, Groener signed a 1-year contract with
FC Twente as the successor of
Hennie Hollink. His contract was extended for one more year in February 1982. Groener finished the season in 12th place, and without showing any signs of improvement the following season, he was released in November 1982 with
Spitz Kohn taking over as manager the team relegated the following season. From 1983 to 1985, Groener returned to the Caribbean as manager of the
Netherlands Antilles. Upon his return to the Netherlands, he managed
Quick '20 once more, followed by a stint as manager of German team
VfL Herzlake competing in the
Oberliga. In 1992, he became the director for Dutch club
FC Emmen, followed by
SC Cambuur and finally
Heracles Almelo where he was fired in 1998. He later became active as a players' agent representing the likes of
Marko Arnautović,
Samuel Armenteros,
Peter Niemeyer,
Georgios Samaras and manager
Jan de Jonge amongst others. == Honours ==