How to Prune black plantain lily?
No pruning required

black plantain lily · Hosta nigrescens
Also known as: black hosta
Grow in fertile soil that does not dry out, in a shady spot away from direct sun and with shelter from cold, drying winds. Mulch annually in spring. Hostas in the ground may need watering during dry spells. See hosta cultivation for more detailed advice
No pruning required