m6A is an abundant mRNA modification that plays various roles in eukaryotic gene regulation. Genetic analysis has revealed crucial developmental roles for m6A in plants, both embryonically and post-embryonically. For example, ECT genes, which encode RNA-binding proteins with a YTH domain able to recognise (‘read’) m6A, were found to be redundantly required for leaf morphogenesis, but the details of how ECTs regulate developmental processes have remained incompletely understood. Now, Laura Arribas-Hernández, Peter Brodersen and colleagues analyse the developmental roles of ECTs in the leaf and beyond. In triple ect2/3/4 (te234) mutants, leaf primordia are initiated at the right time but then show reduced cell proliferation; however, this slower growth period is extended compared with wild type, leading to larger leaves in which cell layer organisation, cell size and cell type are all disordered. The authors find that ECT2, ECT3 and ECT4 proteins are highly expressed in proliferating cells undergoing differentiation in roots and flowers, reflecting a functional requirement: te234 mutants show slow root growth and agravitropism, and defective floral phyllotaxis and patterning. te234 mutants have delayed flowering time, and show less stem growth and slower floral maturation. Importantly, the m6A-binding capacity of ECT2/3/4 is indispensable for these developmental functions. Thus, timely organogenesis in the whole plant is dependent on ECT2/3/4 reading of m6A.