This is the first history of phytotrons, huge climate-controlled laboratories that enabled plant scientists to experiment on the environmental causes of growth and development of living organisms. Made possible by computers and other modern technologies of the early Cold War, such as air conditioning and humidity control, phytotrons promised an end to global hunger and political instability, spreading around the world to thirty countries after World War II. The United States built nearly a dozen, including the first at Caltech in 1949. By the mid-1960s, as support and funding for basic science dwindled, phytotrons declined and ultimately disappeared—until, nearly thirty years later, the British built the Ecotron to study the impact of climate change on biological communities. By recalling the forgotten history of phytotrons, Munns reminds us of the important role they can play in helping researchers unravel the complexities of natural ecosystems in the Anthropocene.