How to Prune daylily 'Killer'?
Cut back flower stems after flowering has finished. Remove dead foliage as required

daylily 'Killer' · Hemerocallis 'Killer'
Grow in fertile, well drained soil, in areas that will not dry out in summer. Prefers full sun, flowering is likely to be reduced in shadier situations. Water freely from spring to summer. See Hemerocallis cultivation for details.
Cut back flower stems after flowering has finished. Remove dead foliage as required