The plant root system is highly regenerative and thus capable of recovering from pruning, which contributes to – and is sometimes necessary for – plant robustness; however the molecular mechanisms of root regeneration until now have remained elusive. Xu et al. (on pp. 1710-1723) assessed the Root-Cutting induced lateral root Number (RCN) under various conditions and found it to be resistant to polar-auxin transport inhibitors, but partially sensitive to auxin biosynthesis inhibitors. RCN is regulated by activation of both auxin biosynthesis, via YUCCA9 and other redundant genes, and polar auxin transport, which leads to enhanced auxin signaling and subsequent lateral root formation.