Using Ireland as a case study, this study examines the economic drivers of the farm afforestation decision for individual farms. Farm incomes and characteristics are observed across the distribution of livestock farmers, using a longitudinal dataset. Potential agricultural and forest income streams are generated and compared in a life-cycle theoretical framework, while the inclusion of attitudinal survey data in the analysis is shown to contribute significantly to the understanding of the planting decision. The study suggests that there is a cohort of younger farmers on larger holdings who might plant if potential forest income is greater than their agricultural income, but we also find that there is a cohort of older farmers on smaller holdings that will never plant, and for whom negative cultural attitudes are stronger than economic drivers. The study concludes that a 'one size fits all' programme based solely on financial incentives may not be the most appropriate means to encourage further farm afforestation and suggests that more targeted approaches may be necessary to nuance incentives to increase afforestation rates and facilitate the use of afforestation as an agricultural greenhouse gas mitigation mechanism.