Beardsley has taught in the departments of landscape architecture at the University of Virginia, the University of Pennsylvania, and the Harvard Graduate School of Design, where he was a Senior Lecturer and Adjunct Professor from 1998 to 2013. Beardsley also served from 2008-2019 as director of Garden and Landscape Studies at Dumbarton Oaks, Harvard’s institute for research in the humanities in Washington, D.C.

At the GSD, he taught lecture courses in the history and theory of landscape architecture; seminars in writing, criticism, research, and thesis preparation; and occasional studios. While there, he co-organized two exhibitions. One celebrated the centennial of the landscape architecture program at Harvard in 2000 and included documentation of contemporary landscape design projects along with installations by the Detroit street artist Tyree Guyton and the sculptor Mara Scrupe. The other was Dirty Work: Transforming the Landscape of Nonformal Cities in the Americas, an exploration of efforts to improve environmental conditions in low-income communities across Latin America. This subject was also the focus of several seminars co-taught with GSD colleague Christian Werthmann and a studio co-taught with Flavio Janches and Max Rohm from the University of Buenos Aires.

At Dumbarton Oaks, Beardsley administered a fellowship program; organized a series of public lectures, colloquia, and symposia; served as general editor of the department’s publications and inaugurated a new series called ex horto, translations of significant texts in the history of landscape design. 

Titles in the series included Prince Hermann von Pückler-Muskau’s Letters of a Dead Man, Jean-Marie Morel’s Theory of Gardens, and The Dumbarton Oaks Anthology of Chinese Garden Literature, edited by Alison Hardie and Duncan M. Campbell. He also created a new program in urban landscape studies funded by the Andrew W. Mellon Foundation; and initiated a program of installations of contemporary art in the institution’s historic gardens and museum. Beardsley also taught intermittently in the landscape architecture program at the University of Virginia between 1985 and 1996 and two semesters at the University of Pennsylvania in 1989-90 and 1992. He was the Belle Ribicoff Distinguished Guest Lecturer in the History of Art at Vassar College in 2005, and the Nadine Carter Russell Visiting Chair in the College of Art and Design at Louisiana State University in 2004-05.

Beardsley received a John Simon Guggenheim Memorial Foundation Fellowship in 1996-97 for the research that led to his essays on virtual and simulated landscapes, and an individual grant from the Graham Foundation for Advanced Study in the Fine Arts in 1992 for his work on the book Gardens of Revelation. He has been a frequent lecturer at museums, art schools, and academic institutions in the United States, Canada, Great Britain, and Japan.