This paper responds to sustainable HCI’s call to design long-term participatory projects with grassroots communities to counter the local effects of climate change and support more viable practices. We contribute a methodological approach to participatory speculative design as a series of interrelated experiments in living, working in symbiosis with a food-growing community moving towards collective resilience and food sovereignty. As an example of sustainability research within HCI, community food-growing has predominantly focused on collaborative acts of growing rather than disagreements, divergences and frictions. Limited attention has been paid to the challenges of effectively negotiating collaborative, sustainable speculative futures in this context. This paper reports on a workshop series on sustainable community food-growing using situated participatory speculation to address potential tensions when working collaboratively towards socio-technical alternatives.