Purpose: Farmers face particular challenges with their mental health and wellbeing programmes are necessary resources of support. This study evaluated the effectiveness of the 'On Feirm Ground' farmer mental health training programme targeted at farm advisors in Ireland. Methodology: Between October 2021 and April 2022, 'On Feirm Ground' Trainers (n = 24) delivered 23 1-day training programmes to 190 participants. This study was conducted on a subset of those training days (n = 17) and participant quantitative and qualitative data was collected pre, immediately-post, and 6-month post-training (n = 112). Findings: 'On Feirm Ground' significantly improved participants' self-reported levels of knowledge, capacity, and willingness to support farmer mental health (P < 0.001). Additional qualitative findings revealed how the training aided advisors in practice, while also highlighting where further supports are required. Practical implications: 'On Feirm Ground' creates increased awareness about farmers' mental health, whilst also increasing the likelihood of farmers speaking out about mental health. Theoretical implications: Our research provides important detail on how pre-existing agricultural support providers can be effective mediators of support for farmer mental health. Original value: The 'On Feirm Ground' programme has succeeded in improving advisors' capacity to support farmer mental health. The long terms effects of adapting programmes to the cultural context of the farmer may increase farmers' utilisation of health services.