Different strands of scientific literature use various terminologies to refer to types of urban spaces without productive function, abandoned and legally uncontrolled. These include at least the following three: “Terrain Vague”, “vacant lot”, and “urban voids”. Although different, they all similarly evoke spaces where emptiness prevails over fullness and is in a perpetual state of suspension. These spaces, because of their characteristics and their temporary complete availability, are used daily by different communities, spontaneously and informally, through different appropriations and uses, and by nature, where species not allowed elsewhere and in the absence of human control find refuge, unusual encounters can occur. Over the last twenty years, a series of projects, activities and practices have begun to emerge in these spaces, such as especially recent park and garden projects in Europe, that retain or incorporate spontaneous vegetation, undefined functions, and a wild aesthetic, reflecting a growing interest in and new appreciation of these spaces, particularly among landscape architects. Among these types of projects and initiatives, those that we will define here as Vague Farm, undoubtedly stand out. By this term, we refer to projects and initiatives that, while mainly based on the creation and management of urban garden and activities related to agriculture and local food production, also aim to preserve some of the informal and spontaneous characteristics of the previous Terrain Vague. This paper proposes a first attempt at defining Vague Farms, through the analysis of five case studies intentionally chosen from different European cities, to show the simultaneous emergence of these practices. To achieve this, it proposes: i) a brief theoretical introduction to Terrain Vague and its relationship with agriculture and communing (theoretical background); ii) a reading of these community urban gardens projects through the lenses of Urban Commons (observed experiences and results); iii) a proposal of a definition of vague farms projects and their characteristics (discussion).