Despite citizens and public incentives call for a deep reduction in pesticide use, the French market-gardening sector faces difficulties to implement agroecological cropping systems that use less pesticides, and in particular crop diversification, because it requires a deep redesign of cropping systems. How to favor the transition of large specialized farms, occupying main part of the total area, those that could enable a strong reduction in pesticide use? Two case studies were carried out in South–East France. Several actors in the agri-food system were interviewed to identify the current barriers to crop diversification. Six categories of barriers faced by market-gardeners were identified: agroecological inputs not or hardly accessible, lack of specific machinery and land, work-related barriers, lack of knowledge, and commercial difficulties. An outstanding result is that most barriers experienced by market-gardeners are linked to barriers experienced by other actors, which highlights a sociotechnical lock-in around the diversification of crop rotation for managing plant health. This information was later used to devise and carry out multi-actor workshops to co-design coupled innovations that enable farmers to overcome the barriers for implementing diversified crop rotations, with the main actors in the agri-food system engaged in the sociotechnical lock-in