Folates are water-soluble B-vitamins that contain tetrahydrofolate (THF) and its derivatives. In plants, they are essential cofactors in C1 metabolism, being involved in the formation of purines and thymidylates for DNA synthesis, production of amino acids and proteins. They play a central role in the methyl cycle. Novel functions of folates in plants have been discovered recently. For example, folates regulate gene expression by the riboswitch, work as the electron donor when phenylalanine is converted to tyrosine, and harvest light as the coenzyme of photolyase and plant cryptochrome. Moreover, folate is involved in chlorophyll biosynthesis and oxidative tolerance of seeds, for example. We review these discoveries and give prospects for plant folate research.