Born to Thomas and Mary Ann Withycombe in Devonshire, England, English tenant farmers in 1843. Withycome emigrated to the United States with his parents in 1871, settling on a farm near Hilsboro, Oregon. After turning 17, he spent four years working on his father's farm. In 1873, Withycomb purchased his own 100 acre parcel on the Horace Lindsay Land Claim, later expanding his holdings to 256 acres. Agriculture became Withycomb's passion, becoming a prosperous livestock breeder and establishing a reputation as a sucessful scientific farmer.