How plants gather their resources, harvest solar energy and convert raw materials into an increased biomass is one of the enduring fascinations of biological science. Just about every step has been charted by biochemists and few processes have escaped the determination of a rate constant by physiologists. Even the molecular biologist is busy identifying the genes that govern the processes of synthesis and assembly. Nevertheless, at higher levels of organization, of building populations and, especially, communities, the prediction of growth continues to be problematic. Thus, the development by Bright & Walsby (pp. 301–316 in this issue) of a method for calculating the daily growth of a photoautotroph in its natural environment is bound to command our attention. Their approach is ingenious and the veracity of their calculations compelling. This is exciting science.