Upscaling perennial biomass crops (PBC) for bioenergy is a key element of decarbonisation plans in the UK. However uptake of PBC by farmers has been historically poor and the bioenergy industry nascent, reflecting international contexts. This has been problematised from a number of social, economic and policy perspectives and scales. Positioning this work in transition studies, we aim to examine barriers and enablers to upscaling Miscanthus and SRC willow feedstock for bioenergy and greenhouse gas removal in the UK. This study applies a conceptual framework that inserts farm level perspectives such as sociocultural motivations into an Innovation Systems (IS) functions approach. Qualitative data was collected in semi-structured interviews and participatory workshops with farmers (PBC growers and non-growers) and selected IS stakeholders (advisers, land agents, biomass industry intermediaries/supply chain, agriculture, environment, forestry, policy and NGO representatives). Analysis was structured around seven IS functions considered necessary for IS build-up, integrating macro and micro levels. This approach offers a deep integrated understanding of barriers and enablers to upscaling PBC. Results showed misalignment of the IS functions which are iteratively entangled with farm level actors’ social processes and decisions, something which have hitherto been little understood or theorised in the bioenergy context. Identifying potential intervention points to improve system performance and understanding how farmers and other stakeholders negotiate demands for PBC are particularly relevant to policy makers’ ambitions for large scale planting and GGR projections.