[Sven]

Forget the pots and stick the root cuttings directly in the soil about 1-2” deep. Keep it moist. Plant it in full sun, partial sun, everywhere to see where it likes it best. It needs about 8 hours sun per day. It does like moisture, so if in direct sun, mulch heavily to keep moisture in the soil.

Mullein can dry out and die in a day or two if not deeply rooted. It likes rocky areas and perhaps a bit of shade midday.

Plantain can grow almost anywhere, mine seems to grow best in dappled sun, shaded areas.