Born in England, Stensson immigrated to Canada in 1914, when his father answered an advertisement in an English journal to run a nursery founded by landscape architects Howard and Lorrie Dunington-Grubb, in Sheridan, outside of Toronto. He studied architecture at the University of Toronto, and landscape architecture at Harvard, earning his M.L.A. and receiving the Charles Eliot Traveling Fellowship in 1934. In 1935 he partnered with the Dunington-Grubbs in their landscape architecture firm, but in 1939 became the managing director of Sheridan Nurseries, and its president in 1965.
One of Stensson’s first major projects in partnership with the Dunington-Grubbs was the landscape design for Graydon Hall Manor, an estate built on 40 hectares of farmland east of Yonge Street in Toronto. He worked on several private gardens in the 1930s, and also contributed to the design of the Oakes Garden Theatre and the Rainbow Gardens for the Niagara Parks Commission, at Niagara Falls. There he worked closely with Howard Dunington-Grubb and architect William Somerville to create a Beaux-Arts landscape around a sloping, grass theater, connected to the Rainbow Bridge by Art Deco-style gardens. Stensson was one of nine founding members of the Canadian Society of Landscape Architects and Town Planners (now the Canadian Society of Landscape Architects) in 1934, and its president in 1938 and 1948. He belonged to several professional associations, and was a president of the Canadian Nursery Landscape Association from 1954 to 1955. He passed away at Toronto’s Queensway Hospital at the age of 64.