[1] Born in Hanover during the Weimar Republic, Dahlgrün attended the Hanoverian Kaiser-Wilhelm- und Ratsgymnasium Hannover [de] and passed his Abitur there.
[2] At the time of the reconstruction of the city, 48 % of which was destroyed by the bombing of Hanover in World War II,[3] the Filmtheater was opened on Kröpcke 1953 with a festive prelude by Dahlgrün on Grand piano.
He initiated the international exchange of the Hanoverian Academy of Music with institutes in cities such as Brussels, Copenhagen and Milan.
[1] Dahlgrün was temporarily chairman of the Deutscher Tonkünstlerverband as well as the Lower Saxony state committee of the Jugend musiziert.
As a long-standing member of the "Hannoversche Künstlerverein"(HKV), an association for artist, , Dahlgrün was its chairman from 1966 until his death in 1982.