How to Prune dense ginger lily?
No pruning required other than cutting back the foliage and old flower spikes at the end of the season

dense ginger lily · Hedychium densiflorum
Outdoors, grow in humus-rich, moist but well-drained soil in sun or partial shade. Shelter from cold winds and apply a deep mulch of garden compost or leafmould to protect the rhizomes in frost prone areas. Under glass use a loam-based compost such as John Innes No 3 and grow in bright, indirect light
No pruning required other than cutting back the foliage and old flower spikes at the end of the season