Harry and his siblings initially moved to his maternal grandparents' ranch in Montana, and then to a family wheat farm in Umapine, Oregon.

[2] Wellman served in the United States Navy through World War I[3] after his father died in 1917.

[2] Wellman became a naturalized citizen of the United States and graduated from Oregon Agricultural College in 1921.

He married Ruth L. Gay following graduation, and was the 4-H Club agent of Malheur County, Oregon.

He returned to Berkeley in 1935 after serving a year in Washington, D.C., as chief of the General Crops Section of the United States Agricultural Adjustment Administration.