CONTEXT The fast acceleration of climate changes contrasts strikingly with the slow implementation of any globally-coordinated mitigation response to climate threats. In many countries, the current priority is to maintain food production and avoid food crises through the adaptation of vulnerable agricultural systems. In this context, the introduction in crop rotations of hardy crops such as sunflower, which are more tolerant to droughts and more resistant to pests, has the potential to harness solutions based on ecosystem services instead of synthetic input. OBJECTIVE This article tackles the issue of farmers’ varietal innovation development and adoption with the intent to highlight pathways for more resilient and sustainable agricultural systems. In particular, it explores the governance of the French sunflower varietal innovation system to assess its legitimacy. The objectives are therefore (1) to provide a relevant institutionalist framework based on the concepts of governance and legitimacy, and (2) to discuss opportunities to unlock the current situation that sees varietal innovation not entirely responding to the needs of farmers. METHODS The analysis relies on 37 semi-structured interviews with farmers, representatives of seed companies and seed distributors, as well as scientific experts in Occitanie and Nouvelle-Aquitaine, the two regions leading sunflower production in France. The interviews explored sunflower strengths and weaknesses, sunflower genetic traits sought by farmers, the adoption and diffusion of sunflower varieties, and the impacts and perceptions of both public policies and climate changes. RESULTS AND CONCLUSIONS Results show that the current lack of governance legitimacy of the French varietal innovation system is counterbalanced by the critical role of seed distributors representatives who contribute to maintaining trust. In order to improve the effectiveness of climate changes adaptation efforts, the normative legitimacy of the current varietal innovation system may gain from the inclusion of farmers in the governance of the varietal innovation system and the implementation of a more cognitive legitimacy. SIGNIFICANCE This article contributes to the economic literature through an investigation of varietal adoption in the Global North on a crop cultivated for its environmental benefits, instead of focusing on a staple food crop in the Global South. It adopts a comprehensive stance that departs from the numerous econometric analyses classically used to investigate varietal adoption. The institutionalist perspective provides conceptual tools to deepen recent results of the systems thinking literature focused on the concepts of governance and legitimacy.