Gene regulatory networks controlling cellular differentiation must sense changes in environmental conditions and coordinate gene expression with cell-division cycles. However, the mechanisms of sensing and integrating different signals remain elusive even for the best studied model systems. Here we uncover a simple solution to this complicated task by investigating the Bacillus subtilis sporulation network. We show that this network evaluates the level of starvation without specific metabolite sensing by detecting changes in cellular growth rate. In addition, the arrangement of sporulation network genes on the chromosome allows the network to coordinate its response with cell cycle by exploiting the transient gene dosage imbalance during chromosome replication. These design features allows cells to decide between sporulation and continued vegetative growth during each cell cycle spent in starvation conditions. The simplicity of this cell-fate decision mechanism suggests that it may be widely applicable in a variety of gene regulatory and stress-response settings.