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

red ginger · Hedychium greenii
Outdoors, grow in humus-rich, moist but well-drained soil in sun or partial shade. Shelter from cold winds and consider 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 on in bright, indirect light
No pruning required other than cutting back the foliage and old flower spikes at the end of the season