Plants coordinate their growth and development through complex regulatory networks involving changes in the expression of thousands of genes. Many developmental pathways are regulated at the level of messenger RNA (mRNA) through alternative choices in mRNA processing. These choices can have consequences for the localization, stability or translatability of mRNAs. One of the key ways in which RNAs are processed is by the methylation of the RNA base adenosine-a modification known as m6A. Even though it was first discovered in the 1970s, the biological significance of m6A marks has only recently become clear. In this feature article, we identify the factors controlling the writing and reading of m6A modifications in plants. We also highlight some of the features of plant development that depend on m6A and explore the recently discovered molecular mechanisms that use m6A to control development or response to environmental stress.