<p>Organic farming is central to the sustainability goals of the European Union, yet it remains marginal in intensively farmed regions such as Flanders. Taking up the notion of systemic lock-in, we examine why organic vegetable farming struggles to expand in this region and why a strategy developed in a participatory systems mapping workshop converged on a bounded set of actions perceived as feasible by participants. Findings reveal how multiple mechanisms jointly hamper the sector’s expansion and its distinctiveness from conventional agriculture. These include competition for scarce land and seasonal labour, retailer driven pricing and standard specifications, exposure to imports and macro-economic shocks, and a knowledge–policy bias towards sustainable intensification solutions. To overcome these struggles, participants prioritised coordination measures within existing mandates and institutional relationships, including raising consumer awareness, seeking commitments across the value chain to secure sales channels and a steady local supply, dedicated advisory services and public procurement. By overlaying the participatorily developed Theory of Change onto ex post refined system maps, we make the scope and limits of the designed interventions analytically visible. Ex post analysis indicates that these measures leave the engine behind the on-going agro-industrialization in the region intact and leave the organic vegetable sector vulnerable to wider shocks and trends. The boundedness of the resulting portfolio reflects the effects of participation and goal framing, the institutional context and changing political-economic conditions. We conclude with analytical implications for participatory strategy design and discuss implications for building transformative agroecological politics and policy.</p>