How to Prune stinking iris?
Remove any dying foliage in autumn

stinking iris · Iris foetidissima
Also known as: blue seggin; gladden; gladdon; gladwin; gladwyn; roast beef plant; scarlet-seeded iris; stinking gladwin; stinking gladwyn
Grow in well-drained, neutral to slightly acid loam but will tolerate most soils in full sun, partial shade or shade
Remove any dying foliage in autumn