Fennel is considered both a vegetable and herb due to its wide ranging nutritional and healing benefits.
The Fennel herb (Foeniculum vulgare) has a long history of use. The Egyptians and the Chinese used it strictly for medicinal purposes in early history.
During the Middle Ages, it was believed to hold magical qualities and people hung fennel plants over their doors to drive away evil spirits.
Eventually, someone recognized its use as a flavoring for eggs and fish. Today, its crisp anise-like flavor makes it a favorite of cooks everywhere.
Native to southern Europe, the fennel herb is now naturalized throughout Europe, North America and Australia and grown in gardens all over the world.
Fennel is rich in folic acid, vitamin C, magnesium, cobalt, iron, and essentials oils that contain powerful anti-bacterial and anti-fungal properties.
Fennel is excellent for indigestion and is commonly used as a natural antacid in order to help reduce acidity and inflammation in the digestive tract and to facilitate proper absorption and assimilation of nutrients from food.
Fennel has potent anti-flatulent and carminative properties which means it is able to prevent and stop the formation of gas in the stomach and intestines.
Fennel is also known to be highly beneficial for sinus congestion, bronchitis, renal colic, anemia, hypertension, macular degeneration, constipation, bloating, diarrhea, and irritable bowel syndrome. Fennel is used to help protect against both cardiovascular disease and cancer.
Fennel contains an important anti-inflammatory phytonutrient called anethole that blocks both inflammation and carcinogenesis, which is the mutation of regular cells into cancerous cells.
Fennel also has the ability to ease and regulate menstruation by regulating hormonal action properly in the body.
Fennel is used amongst nursing women to help stimulate consistent milk flow for their babies.
Fennel is known to help strengthen hair, prevent hair loss, relax the body, and sharpen the memory.
Fennel seeds can be chewed after a meal to aid in digestion and to remove bad breath.
Fennel seeds can also be made into an effective medicinal tea by steeping the seeds in hot water for 10 minutes or more.
Fennel’s aromatic taste is reminiscent of licorice and anise and it’s texture is similar to that of celery, having a crunchy and striated texture. Fennel is one of the important ingredients of Chinese Five Spice.
Fresh fennel juice can be combined with fresh celery, cucumber, and/or apple juice for a healing and medicinal drink. Fresh fennel juice can also be used topically to swollen or inflamed eyes to reduce irritation, swelling, and fatigue.
Fresh fennel has a crunchy, slightly sweet licorice flavor and is a wonderful addition to fresh salads, smoothies, soups, stir-fry, potatoes, and other vegetable dishes.
Fresh fennel and fennel seeds can be generally found at your local supermarket or farmer’s market.
Fennel tea, capsules, tincture, and extract can all be found online or at your local health food store.
Growing
Planting fennel by seed is the much easier option. Seed can be sown as soon as the soil warms in the spring. 
Soaking your seeds between wet paper towels for a day or two before sowing will ensure better germination.
Keep the area moist until the seeds sprout and thin the fennel plants to 12 to 18 inches apart when they are 4 to 6 inches tall. Plants will begin flowering about 90 days after planting.
Choose a sunny location in the back of a well-drained bed. The fine textured foliage can grow up to 6 feet tall and makes an excellent backdrop for other flower planting.
Fennel is a short lived perennial that blooms best in the second year. It readily re-seeds and while not considered invasive, it has certainly earned its reputation for aggressive growing.
Fennel can be cut back early in the season to encourage bushier growth and should be deadheaded for seed harvest and to prevent over seeding of new plants.
Harvest and dry seeds as the flower heads fade. There’s only one restriction to how to grow fennel: don’t plant it near dill as cross pollination results in strangely flavored seeds for both plants!
Fennel prefers acid soil, appreciates the occasional dose of mild fertilizer and a little additional water if the weather is hot and dry.
In addition to its kitchen contributions, planting fennel will attract beneficial insects to the garden and its leaves are a favorite with the caterpillars of the swallowtail butterfly.
For more research:
http://www.medicalnewstoday.com/articles/284096.php
http://www.whfoods.com/genpage.php?tname=foodspice&dbid=23
https://www.organicfacts.net/health-benefits/herbs-and-spices/health-benefits-of-fennel.html
