Born in Switzerland, Wirth expressed an interest in horticulture from a young age, working as a gardener, commercial florist, and floral designer in London, Paris, and Zurich, before moving to New York in 1888. He was employed by New York City’s Department of Parks as a gardener while studying landscape gardening after-hours. There he attracted the attention of Superintendent, Samuel Parsons, Jr.
In 1896 Wirth became Superintendent of Parks in Hartford, CT implementing plans by various principals of the Olmsted firms. In 1900 he designed the master plan for Elizabeth Park, where he included the country’s first public rose garden. In 1906 he became Superintendent of the Minneapolis Park System, overseeing 57 properties on approximately 1,800 acres. In his 30 years of tenure, the system grew to 144 properties covering 5,241 acres. With many acquisitions, the park system effectively positioned a park within six blocks of every city resident. Wirth’s son, Conrad, was a director of the National Park Service.