Common fennel, or Foeniculum vulgare, also known as sweet fennel, belongs to the parsley family. Widely grown as an ornamental perennial due to its soft, feathery foliage that often towers 6 feet or more in height, common fennel produces long stems that offer excellent, crunchy flavor when consumed raw. The seeds of the plant can flavor a wide variety of culinary dishes, desserts, candies and pastries, according to Floridata. The leaves make attractive garnishments and can be added to salads. Common fennel grows well, produces thousands of seeds and can easily escape cultivation with its invasive tendencies.
Cut small quantities of the common fennel leaves and stems when the plant reaches 6 inches in height. Use pruning shears to clip away the leaf. Remove only the top 2 inches of the leaf when harvesting.
Harvest the umbels of the fennel plant when they begin to dry and change color. The umbels usually begin to dry in late August. The fruiting umbels quickly turn tan. Promptly clip the umbels before the seeds are spread.
Place the cut seed umbels into a paper bag so the seed dispersal occurs in a contained environment. The seeds will fall to the bottom of the bag within a few days of clipping the umbels.
Store the seeds in a glass jar in a dark location for six months before consuming. Allowing the seeds to continue drying out in a jar for an extended time period will increase their liquorish flavor.