Tree-ring growth is a daily scaled process, where endogenous and environmental components orchestrate wood formation through a series of developmental events that can be monitored studying plant phenology. Recent studies demonstrate that the temporal dynamics of wood formation inferred from phenology monitoring are excellent markers of tree sensitivity to weather and climate fluctuations. Encompassing for acclimation and adaptation components, wood developmental dynamics provide indeed for excellent metrics to predict tree-ring growth and productivity. However, a mechanistic understanding of these processes remains beyond our grasp, hampering the implementation of process-based models to predict tree-ring growth. Relating wood phenology with plant development and the resulting xylem cell traits, we scratched the surface of a more holistic understanding of tree growth, with timely information to assess and deal with the impacts of climate change and global warming.