Your translation seems good enough to me, but on the other hand I can't find a source for your quote using Google
Re:Nietzsche on Solitude
by will_work4tears on Monday August 17, 2015 @01:40PM
(#10074741)
Closest that I could find was: "Talent is nurtured in solitude … A creation of importance can only be produced when its author isolates himself, it is a child of solitude."
I think it was Goethe, another great German thinker and poet, who once said: "In der Einsamkeit geschehen die größten Dinge." - "In Solitude the greatest Things happen."
P.S.
I'm not sure if my 'tanslation' reflects the original meaning of the sentence. Please, feel free to correct me if I'm wrong.