The complexity of gene regulatory networks in multicellular organisms makes interpretable low-dimensional models highly desirable. An attractive geometric picture, attributed to Waddington, visualizes the differentiation of a cell into diverse functional types as gradient flow on a dynamic potential landscape, but it is unclear under what biological constraints this metaphor is mathematically precise. In this talk, I will show that gene regulatory strategies that guide the growth and development of a single cell to a target distribution of cell types are described by time-dependent potential landscapes, under certain specific growth-control tradeoffs. The theory highlights a conceptual link between nonequilibrium thermodynamics and cellular decision-making during development.