This essay explores the faultlines, poetic pressures and social structures of feeling determining poetry ‘after’ Hiroshima. Nuclear bombs, accidents and waste pose theoretical and poetic challenges. The argument outlines a model of nuclear implicature that reworks Gricean conversational implicature. Nuclear implicature helps to describe ways in which poems ‘represent’ nuclear problems implicitly rather than explicitly. Metonymic, metaphorical, and grammatical modes of implication are juxtaposed with recognition of social attitudes complicit with nuclear problems. Mushroom and lichen metaphors are analyzed and distinguished. There are brief accounts of The Chernobyl Herbarium, The Nuclear Culture Source Book and poems by Aidan Semmens, Lorine Niedecker, George Oppen, Denise Levertov, Adrienne Rich, Allen Ginsberg and Gerry Loose. The argument attempts to keep open the fragile agency of writing in poems that confront nuclear power. Poetry after Hiroshima is also contrasted with Adorno’s provocative questions about poetry after Auschwitz, amid cold war arguments that have distorted recognition of the reality of nuclear production. The essay concludes by considering the emergence of poetry within E.P. Thompson’s theoretical account of ‘Exterminism’, sketching ways in which poetics and theory might inform both the nuclear imagination and the difficulties of nuclear song.