Del Tredici is a botanist and senior research scientist at the Arnold Arboretum of Harvard University, where he has worked since 1979. While he has been doing research in various areas of the plant sciences, his primary goal has always been to bridge the gap between horticulture and botany. Del Tredici's interests are wide-ranging and cover such topics as plant morphology, conifers, bonsai, urban horticulture, plant/microbial symbioses, and tree architecture. He is a specialist in the evolution, natural history and cultivation of the Ginkgo tree. He has worked as a plant propagator at the Arnold Arboretum for ten years as the editor of Arnoldia for four years, and Director of Living Collections for ten years..

Del Tredici received his BA in zoology from the University of California at Berkeley in 1968 and his PhD in biology from Boston University in 1991. He is published widely and the winner of the Arthur Hoyt Scott Medal and Award for 1999—an award presented annually by the Scott Arboretum of Swarthmore College "in recognition of outstanding national contributions to the science and art of gardening."