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 2.84 sec(-1) with feruloyl-CoA as substrate. Optimum pH is 6.5. Phenylpropanoid metabolism. Mostly expressed in tubers, and, at low levels, in underground stems, stems, leaves and petioles. Transiently induced at low levels 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.