Considering the importance of visual representations for communication between stakeholders in landscape planning and design processes, the authors identify a lack of critical visual research methods supportive of the disciplines involved. As part of such a method, they have developed an analytical framework based on semiotic and iconographic theory that enables a visual content analysis and iconographic interpretation of landscape design representations. Two projects from Rebuild by Design, a participatory transdisciplinary design competition organized in the New York City area after hurricane Sandy, were analysed to demonstrate this framework. The article presents a semiotic vocabulary based on four categories: medium, mode, formulation and knowledge with which to ‘read’, discuss and potentially create design representations. This enables a syntactic analysis for assessing the semiotic complexity of design representations in terms of validity, readability and interactivity. This assessment enables further qualitative study of the production and interpretation of landscape design representations in practice.