Little is known about Siedle's early life or training. Siedle worked in the theatre when British pantomime and Viennese operettas were still being produced, but American musical comedies were becoming increasingly popular. She worked with
Ziegfeld,
Lew Fields,
Charles Frohman, and the
Shuberts. She worked with scene designers such as
Homer Emens, Ernest M. Gros, Frank Dodge,
Ernest Albert, Joseph A. Physioc, and Francis Gates and Richard Gates. Siedle worked on thirteen productions with
Julian Mitchell. Upon her death, Mitchell said, "Death in removing Mrs. Siedle, has deprived me of the helper who enabled me to make my reputation. Without her assistance I should never have been able to carry out the musical comedy color schemes which have made beautiful stage pictures. Her taste was always good, and her ability to design amounted to genius." ==Costume Designs==