Raised in Auburn, New York, Cowell attended Cornell University’s agricultural program, where he established a chapter of Alpha Zeta (a professional agricultural fraternity) and from which he received a B.S. in 1903. As illustrated by his masters thesis, entitled The Small Formal Garden: its Principles and American Use, Cowell’s interests lay with landscape design, and he worked as a landscape architect in Pittsburgh and Philadelphia after graduating. In 1913, Cowell moved to State College, Pennsylvania to establish the Department of Landscape Architecture at Pennsylvania State College. Continuing to practice, Cowell was seminal in laying out the grounds of Awbury Arboretum, in a suburb of Philadelphia, between 1919 and 1930. Around the same time, he designed the formal gardens at the Cairncrest estate in Bryn Athyn. By 1920, Cowell had laid out a portion of East College Heights, a residential neighborhood in State College where he resided. After retiring from teaching in 1925, Cowell continued his professional practice, working throughout the Mid-Atlantic and the Southeast. Some of his projects include Oglesby Park in Wheeling, West Virginia; Evergreen Gorge Cemetery, in Erie, Pennsylvania; numerous River Road estates in Louisville, Kentucky, and the Pennsylvania Capitol Grounds in Harrisburg.