The circadian clock provides a fundamental timing mechanism for plant fitting to seasonal changes in the photoperiod. Although photoperiodic regulation of developmental transition has been studied in several species, our understanding of core circadian clock parallelisms across species is sparse. Here we present a comparative analysis of circadian clock networks by identifying common regulatory principles that govern key genes in photoperiodic developmental transition. Using time-course transcriptomic datasets from long-day plants and short-day plants taken in different photoperiods, we propose a model that integrates a minimal set of circadian clock components to predict the necessary conditions governing species-specific clock outputs. This study identifies regulatory patterns associated with circadian clock function across different plants, linking photoperiod interpretation with minimal clock architecture.