Climate change requires us to fundamentally change the way we plan and develop our cities and regions. This raises questions about the role and capacity of spatial planning in general and the agency and expertise of planners in particular. Based on 27 qualitative interviews with Swedish planning professionals, we identify four key constraints: the increasing politicisation and complexity of planning practice, a cultivated practice of bypassing planners' expertise and a loss of control over their own professional sphere. Our findings suggest that the Swedish planning community is 'congealed' rather than agile when it comes to promoting zero-carbon cities and regions.