Deadheading
You can cut back spent flowers at the base of the flower stalk, if seed is not required for propagation. This will prevent the plant spending energy on seed production, conserving resources in the bulb for next year’s display.
Cutting back bulb foliage
Wait for a minimum of six weeks after the end of flowering before cutting back the dead foliage, and ideally only remove foliage when it is yellow or brown and straw-like. Until this time, the bulbs should be watered and fed as above. Also, do not tie or knot the leaves.