Stewart taught sciences including biology and physics at Illinois high schools before and during his time at Illinois State. He also studied horticulture at Cornell University, receiving his A.B. in 1902.
Stewart was later a professor at Pennsylvania State University as well as a fruit grower, botanist and horticulturist.[4] He died at his York, Pennsylvania home in 1922. At the time of his death, he was the head of the department of pomology at Penn State.[5]