More-than-human-centred design is a growing field in HCI (human-computer interaction) that account for non-human actors in design processes (such as animals, plants, and microbes but also autonomous technologies). While the rationale for more-than-human-centred design is clear, there is a lack of design methods grounded in this thinking. We articulate the idea of noticing as a method for approaching design spaces as systems of mutual interdependence between organisms. The findings are based on a longitudinal ethnographic study of urban farming—including the study of urban farmers’ practices and use of technologies with a focus on the interplay between humans and non-humans, such as plants and microbes. We articulate noticing as a phenomenon and show examples of urban farmers’ practices of noticing. We discuss principles for designing with the interdependencies of several organisms based on what is noticed in a setting. We argue that the way we have separated ideas about the environment and human experience is a part of the sustainability problem—and suggest noticing as an approach that instead combines positive human experiences and the needs of the environment.