How to Prune plantain lily 'Snow Mouse'?
Remove spent foliage as required and clear up dead foliage when it dies back at the end of the growing season

plantain lily 'Snow Mouse' · Hosta 'Snow Mouse'
Grow in fertile, moist but well-drained soil in full or part shade with shelter from cold, dry winds. See hosta cultivation for further information
Remove spent foliage as required and clear up dead foliage when it dies back at the end of the growing season