Upstream engagement seeks to understand and address social and ethical risks early in science and technology development. However, questions remain about who to engage and what kinds of insights different publics can contribute, a core dimension of responsible research and innovation. Across fifteen upstream survey events (n = 397) conducted in the Northeastern and Midwestern United States and in Italy, this study examines how diverse publics conceptualize an emerging agricultural biotechnology known as programmable plants. Qualitative analysis of the 765 open-ended responses identified three themes: 1) Making sense of programmable plants, where respondents reflected on what programmable plants could mean and represent, 2) What makes plants programmable, where respondents imagined mechanisms and metaphors for altering plants, and 3) What programmable plants make, where respondents articulated desired applications and outputs for programmed plants. The quantitative analysis revealed that professionals had higher expected mentions of technical applications emphasizing plant-environment-human interactions, the general public emphasized naturalness, though rarely, and students comparatively expressed more uncertainty, also rarely. The findings demonstrate how open-ended upstream engagement reveals diverse interpretations of programmable plants across stakeholder groups, emphasizing the importance of inclusive public engagement as digital innovations in agriculture continue to advance.