This article presents the results of a public engagement experiment on a project trialling 'vertical farming', an emerging technology addressing urban food issues. The experiment developed within an issue mapping project, analysing debates about vertical farming on the digital platforms, Twitter and Instagram. The article presents a software tool designed to engage 'offline' publics in the issue mapping process, using images collected from Instagram. We describe testing this software tool with visitors to exhibitions of vertical farming in two science and technology museums. Our findings highlight the predominance of commercial publicity about vertical farming on Twitter and Instagram and the organisation of public attention around technological novelty. The article discusses the challenges such publicity dynamics pose to mapping issues on platforms. We suggest some ways digital methods might contribute to public engagement with technologies, like vertical farming, that are a focus of organised commercialised innovation.
Keywords: digital methods; emerging technologies; issue mapping; participation; platforms; public engagement; vertical farming.