With a style inspired by the Englishman
Nat Gonella, he guested in 1938 in leading orchestras such as
Hot Dogs and . Before his musical career, he was also one of the country's leading cyclists. As a member of
SK Rye, he was Oslo champion in 1937 in the 1000 metres track cycling and 20 km road cycling. The following year, he won the team championships at the junior National Championships in 20 km road cycling. After trips to England (1938–39) with Vic Lewis and
George Shearing, he was a central part of
Oslo's swing-jazz milieu, where he led his own
Rowland Greenberg Swing Band (1939–41) with
Arvid Gram Paulsen on sax, on piano, and
Pete Brown on drums. He also led his
Rowland Greenberg Rytmeorkester (1940–44), with
Gordon Franklin on tenor sax,
Arvid Gram Paulsen on alto sax,
Robert Normann on guitar, , Frank Hansen, on trombone, and
Fred Lange-Nielsen on bass. A record release (1942) was banned by the German regime, and he was jailed for breaching the
Rytmeklubbforbundet by viewing jazz films (1943). After his release from
Grini, he was also active in
Sweden (with
Cecil Aagaard,
Thore Ehrling, and ) and England (with
Jimmie Woode and ). He also toured Norway with his own band (1948–50), including presenting
bebop to the country. Greenberg took part in the "All-Star Trumpets session" (Paris Jazz Festival, 1949) with
Miles Davis,
Bill Coleman,
Jimmy McPartland and
Aime Barelli. Greenberg also played with
Charlie Parker who joined Greenberg in his
Sweden tour band (1950), along with
Louis Armstrong (1952), and
Down Beat, who gave Greenberg the first chart placing of his career. During the 1950s, he played extensively in the orchestras led by
Egil Monn-Iversen, and
Terje Kjær. He led his own orchestras including
Mikkel Flagstad on piano,
Totti Bergh on saxophone,
Knut Young on bass, on piano,
Bjørn Krokfoss on drums (until 1981), and played with
Ben Webster (
Moldejazz, 1969) and
Teddy Wilson. ==Awards==