This essay adopts a planning-historical perspective to explore the intersection of space, time, and value struggles through the concept of fallowness. Defined as the condition in which a resource or productive force is intentionally set aside to accumulate potential value for future realization, fallowness is examined across different historical formations of capitalism. The article traces how practices of leaving land, space, or labor temporarily idle have been central to strategies of accumulation, governance, and social reproduction. More broadly, the paper traces diverse configurations of fallowing and speculation as they articulate heterogeneous geographical and temporal formations at particular historical conjunctures since the rise of capitalism. Rather than treating fallowness as a mere condition of vacancy, the text interprets it as a broader socio-spatial strategy through which different regimes organize the relationship between production, reproduction, and the timing of value realization. In this sense, fallowness reveals how spatial arrangements and temporal delays are mobilized to structure economic processes and political struggles over the definition, distribution, and extraction of value. The discussion concludes by considering the potential implications for radical design, understood as a project that connects particular sociomaterial orders to concepts of production and social reproduction, opening possibilities for rethinking planning and spatial practice in more equitable socioecological directions.