Despite growing research on the associations between environmental conditions and mental health, no previous study has collected both quantitative indicators of farm-scale ecology and validated measures of farmer mental health. We assessed whether on-farm factors of engaging in natural resource management (NRM), the environmental state of the farm, or perceived financial challenges were associated with mental health and wellbeing in farmers. A cross-sectional survey was conducted in an established cohort of farmers for whom ecological monitoring data were collected, with data linkage to vegetation and biodiversity indicators. Participants were 63 farmers residing or working in the Box-gum grassy woodlands ecological region of eastern Australia. Primary outcome measures were symptoms of depression, anxiety, life satisfaction and wellbeing. Based on both zero-order correlations and regression models, financial struggle or financial worry were associated with poorer mental health and wellbeing outcomes, as was younger age. There were no direct associations of vegetation cover, avian biodiversity or NRM engagement with mental health or wellbeing. There remain considerable challenges in quantifying the effects of farm ecology on mental health outcomes. Further investigation of the potential social and financial benefits of natural asset management may be warranted.