Fruit production is among the crops using the most pesticides, affecting both the environment and human health. Previous experimentation have shown the limits of substitution strategies to reduce pesticide use. In this context, the INRA Gotheron experimental station (Drôme, France) aims to redesign a pesticide-free orchard maximizing ecosystem services, especially pest control. To overcome the lack of hindsight and knowledge, a co-design workshop was organized with stakeholders from diverse professional activities and experiences. Four prototypes of fruit tree agroecosystems were designed that combined a range of means to suppress pests and proposed original spatial arrangements and layout. The workshop analysis aimed to understand i) which knowledge was brought and by whom, ii) how ideas were elaborated and, iii) the successive steps in the design process. Considering the workshop, the exchanges more than the outputs were source of interest for participants. A fine-grained qualitative approach was adopted and emphasizes the diversity of knowledge brought in by the participants. The ideas finally adopted resulted from negotiations between participants who expressed their support or questioning and suggested alternative or enhanced proposals. Idea elaboration was not a linear process with movements back and forth between exploration and “stabilized” knowledge, between breakthrough and reality, generally ending in trade-offs. This work opens doors for further research on agroecological design process and knowledge sharing. Besides basic knowledge, the capacity to produce proposals and to envisage trade-offs is a key-element to foster participatory design process.