When did the opera in which Friederike Grün played Agathe premier ? 
Friederike Grün:  High points from her stage repertoire included the title heroine in Vincenzo Bellini's "Norma", Agathe in Carl Maria von Weber's "Der Freischütz", Leonore in "Fidelio", Rachel in Fromental Halévy's "La Juive", and Valentine in Giacomo Meyerbeer's "Les Huguenots". Der Freischütz:  It premiered on 18 June 1821 at the Schauspielhaus Berlin.
18 June 1821