Barbara is rigth, on the other site of Flensburg (to east) is also a Mariengaarde, a part of the community Sprakebüll.
The german phone directory shows a lot of Teichmüller (german spelling) in Germany, but in Schleswig-Holstein only in Kiel:
Teichmüller, E.
Bebelplatz 3
24146 Kiel