After completing her education at a ladies' seminary at Biebrich-on-Rhine, Zadow became a governess and ladies companion which gave her the opportunity to travel throughout Europe. She settled in London in 1868 and here she anglicised her name to Augusta. Zadow worked as a seamstress in the East End and became politically active as she became familiar with the conditions of sweatshops.

Zadow and her family arrived in South Australia in January 1877. Her husband, Heinrich Zadow became involved in the union movement; he was elected as a delegate to the Eight Hours Union and the Trades and Labor Council. In late 1889 the Trades and Labor Council held a public meeting regarding whether sweatshop conditions existed in Adelaide. At this meeting, Mary Lee (later to become a leader of the women's suffrage movement in South Australia) suggested the formation of the Working Women's Trades Union (WWTU). At the inaugural meeting of the union, held in January 1890, Zadow was elected as its Treasurer. In late 1891 she was nominated as a delegate to the Trades and Labor Council.

By 1893, South Australia was experiencing an economic depression and Zadow established a scheme in which materials were donated and fair wages were paid to unemployed clothes makers to make shirts and undergarments from these materials. This scheme became the basis for the Co-Operative White Worker's Association. Zadow also formed and managed the Distressed Women and Children's Fund and helped women find work as domestic servants and nurses.

During this period Zadow was also actively involved in agitating for women's suffrage believing that if women had the vote they would be better able to improve their pay and conditions. She took the cause to working women. Women were granted the right to vote in South Australia in 1894 (granted Royal Assent in 1895).

In February 1895 Zadow was appointed Inspector of Factories; under the Factories Act of 1894 she was charged with inspecting the conditions in which women and young people worked and oversight of their safety.

Zadow's headstone at West Terrace Cemetery, Adelaide, was paid for by workers; nearly 1000 subscriptions of threepence each were collected by the Trades and Labor Council.