2-oxoglutarate (OG)- and Fe(II)-dependent dioxygenase (2OGD) involved in scopoletin biosynthesis (PubMed:22169019). Converts feruloyl CoA into 6'-hydroxyferuloyl CoA, and, at low efficiency, caffeoyl-CoA into 6'-hydroxycaffeate, but has no activity with p-coumaroyl-CoA (PubMed:22169019). (E)-feruloyl-CoA + 2-oxoglutarate + O2 = (E)-6-hydroxyferuloyl-CoA + CO2 + succinate Binds 1 Fe(2+) ion per subunit. kcat is 2.68 sec(-1) with feruloyl-CoA as substrate. Optimum pH is 6.5. Phenylpropanoid metabolism. Expressed at low levels in tubers, underground stems, leaves and petioles. Transiently induced by fungal (F.oxysporum f.sp. batatas O-17) and chitosan treatments, in association with the accumulation of umbelliferone and its glucoside (skimmin) in the tubers. Belongs to the iron/ascorbate-dependent oxidoreductase family.