The specific spatial context in the densely urbanised northern part of Belgium, Flanders, offers a sort of laboratory conditions to study, design and plan fragments of open space in an urbanising context. A chronological analysis of documents in three periods relevant to Flemish spatial planning policy allows to conclude that one single planning discourse has reigned spatial planning in Flanders already since the design of the first zoning plans 45 years ago. This planning discourse considers city and countryside as two separate and separated entities. Today however, the validity of this dominant discourse is increasingly under pressure. An obvious societal need appears to be growing to turn around the perception of a possible contradiction between city and countryside. In a densely urbanised spatial context, alternative planning discourses should be based on the idea of open spaces that offer complementary services within a partnership between city and countryside.