Wash the leaves with cool water. Blot dry.
Separate the leaves into bunches, each containing five to 10 leaves.
Tie the ends of each bunch with string.
Hang the bunches in a dry area that is well-ventilated. Try not to hang them right against a wall -- maximum air circulation is essential for best results.
Check the leaves every week for dryness. When they are completely dry, they will be brittle. It may take two to four weeks, according to the University of Illinois at Urbana-Champaign Extension.
Store dried fennel in an airtight plastic container.