Plant development goes like clockwork.

The plant circadian clock promotes daily rhythms in the activity of many processes. These rhythms are synchronized to the diurnal day/night cycle by environmental cues such as light and temperature. Output pathways link the clock to particular biological processes, ensuring that they peak in activity at the appropriate times of day or night. Recently, significant progress was made in defining the mechanisms by which output pathways are activated at specific times. Here these issues are emphasized by describing how the clock regulates growth and development throughout the life cycle of Arabidopsis thaliana, including seed germination, seedling growth, stress responses and the transition to flowering. This wide impact of the clock on growth and development appears to provide an advantage by enhancing growth and seed production in different environments.