Landscape Architect, Springfield, IL, 1938-1944; Landscape Architect, Edwin Grohs and Associates, Seattle, WA, 1945-1948; Principal, Roberta Wightman, Landscape Architect, Seattle, WA, 1948-before 2000; Wightman was retired in 2000.

Chair, Washington Association of Landscape Architects, 1962;

Wightman attended a Montessori school that her mother helped to establish; she also attended the Francis Parker School, Chicago, IL, another progressive secondary school; coursework, Oberlin College, Oberlin, OH, prior to 1931; coursework, Middlebury College, Middlebury, VT, 1931-1933; coursework, study at an architecture school in Cambridge, MA, unclear whether it was M.I.T. or Harvard University, 1936; coursework, Cambridge University, Cambridge, England, 1936; B.A. Landscape Arch., University of Illinois, Champaign-Urbana, IL, 1938;

Wightman was born in Chicago, IL, and attended Oberlin College in Oberlin, OH, and Middlebury College in Middlebury, VT; she did some public landscape work for the City of Springfield, IL, before 1944; she came to Seattle, WA, in 1944 to work with Edwin Grohs at University of Washington Arboretum.

Both of Wightman's parents were liberal physicians; her mother, Olive Smithson Wightman, became one of the first female interns at Chicago's Cook County Hospital. Her father, Hugo W. Wightman, was a surgeon.

In 1993, Wightman lived at the Hearthstone assisted living facility, Green Lake, Seattle, WA;