Floral bicolor pigmentation in some cultivars of petunia and dahlia is caused by naturally occurring RNA interference (RNAi). In both species, the chalcone synthase gene is highly expressed only in the pigmented regions of bicolor petals. However, the mechanism by which RNAi is specifically induced in the unpigmented regions remains unknown. In this issue, Kuriyama et al. show that the clear bicolor pattern is established through a bidirectional feedforward loop involving mutual antagonism between Dicer-like 4 and flavonoid aglycons.