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Fennel is a flowering plant species in the carrot family grown for its edible shoots, leaves, and seeds. It is a hardy, perennial herb with yellow flowers and feathery leaves. Native to southern Europe and Asia Minor, fennel is cultivated in temperate regions worldwide and is considered an invasive species in Australia and parts of the United States. The botanical name of fennel is Foeniculum vulgare. It is indigenous to the shores of the Mediterranean but has become widely naturalized in many parts of the world, especially on dry soils near the sea-coast and on riverbanks. Fennel is a short-lived plant and is almost always grown as an annual.

Foeniculum vulgare is a perennial herb. It is erect, glaucous green, and grows with hollow stems. The leaves grow up to 40 centimetres (16 inches) long; they are finely dissected, with the ultimate segments filiform (threadlike). Its leaves are similar to those of dill, but thinner. The flowers are produced in terminal compound umbels 5–17.5 cm (2–7 in) wide, each umbel section having 20–50 tiny yellow flowers on short pedicels. The fruit is a dry schizocarp from 4–10 mm (3⁄16–3⁄8 in) long, half as wide or less, and grooved.[6] Since the seed in the fruit is attached to the pericarp, the whole fruit is often mistakenly called "seed".

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4 - 8 feet

Width-Circumference (Avg)

1 - 3 feet

Approximate pH

5.5 - 6.8

Types of Fennel

There are three main types of fennel:

  1. Sweet Fennel which is used as a herb (Foeniculum vulgare var. dulce)

  2. Florence Fennel, also known as Florence fennel or finocchio, that is treated as a vegetable (Foeniculum vulgare var. azoricum)

  3. Wild Fennel (herb, perennial) (Foeniculum vulgare var. vulgare)

Herb fennel varieties include:

  • ‘Dulce’: sweet fennel with sturdy stems and filigree pinnate green foliage. These biennial plants can grow up to 200 cm and produce large amounts of aromatic fennel seeds in addition to sweet tasting leaves.

  • ‘Finocchio’: biennial, green sweet fennel with aromatic, sweet leaves and seeds. This variety likes to propagate itself by sowing its seeds in the bed.

  • ‘Magnafena’: vigorous fennel variety with shiny, turquoise-green foliage and very large seeds. These plants grow up to 80 cm and remain quite small and compact.

  • ‘Purpureum’: bronze fennel with bronze to copper-brown leaves. This biennial perennial can grow up to 200 cm and spreads by self-seeding if its seeds are not harvested.

  • ‘Rubrum’: bronze fennel with a growth height of 150 – 200 cm and green leaves with a delicate bronze overtone. This variety forms large, fragrant flower umbels that often only produce a few seeds.

  • ‘Smokey’: brown fennel with particularly sweet-tasting leaves. It can grow up to 150 cm and is a hardy perennial.

  • ‘Stonecrop’: sweet fennel that produces seeds that can be harvested in the first year, if sown in early spring. The plants, which grow up to 200 cm, are a paradise for bees for many weeks.

Florence fennel cultivars include:

  • ‘Solaris’: produces large, semi-flat bulbs that are resistant to bolting.

  • ‘Zefa fino’: is a large variety that's ready for harvest in 80 days and is bolt resistant.

  • ‘Orion’: is ready to harvest in 80 days and has large, thick, rounded bulbs with a crisp texture.

  • ‘Di Firenze’: this old Italian variety forms aromatic, large shoot tubers, but unfortunately is less shoot-resistant than today’s varieties. Therefore, it can only be grown in autumn.

  • ‘Finale’: this shoot-resistant variety is great for early cultivation. The round, firm and dense tubers have a good size, a high yield and an aromatic taste.

  • ‘Fino’: this extremely shoot-resistant variety is characterised by its lush, bright white tubers. It can be grown early in the year and has a great taste.

  • ‘Montebianco’: it is best to harvest this early to medium ripe, broad round tuber fennel variety in autumn. The time between sowing and harvest is about 90 – 110 days.

  • ‘Orazio F1’: hybrid variety with uniformly large, thick, rounded tubers. They hardly ever become woody and can be harvested as mini fennels or fully-grown vegetable fennels.

  • ‘Perfection’: this fennel variety produces beautifully shaped, white, flat-round tubers. It is recommended for early cultivation and autumn harvest.

  • Preludio F1′: hybrid variety from Italy with medium-sized, round, white tubers. This shoot-resistant variety is suitable for planting from May to August.

  • ‘Romanesco’: early maturing fennel variety from the area around Rome with large, thick shoot tubers, which can weigh up to 400 g. These plants reach a growth height of about 60 cm.

  • ‘Rondo F1’: this shoot-resistant hybrid variety for summer and autumn harvest is characterised by a high yield and an intense flavour of the tubers.

  • ‘Selma’: this shoot-resistant variety is fast growing with large tubers. It also stands out for its high yield throughout the summer and its fine flavour.

Wild fennel

The perennial wild fennel is not only closely related to anise (Pimpinella anisum), caraway (Carum carvi) and dill (Anethum graveolens) but is also the original form of today’s garden fennel varieties. It is native to the Mediterranean and the Near East and has been valued as a spice and remedy for thousands of years. Back then, it was mainly used to flavour bread and wine and to treat digestive disorders. Wild fennel is also known as bitter fennel and only forms a very small bulb. The plants, which grow up to 150 cm in height, are perennial and sprout again every spring. Nowadays, wild fennel is grown for its seeds, which are more aromatic than cultivated fennel and have a strong taste, similar to liquorice. It is called bitter fennel due to the camphor-like and bitter-tasting fenchone contained in the seeds, which has an antibacterial and invigorating effect. The dried, yellow, sweet-spicy fennel flowers called fennel pollen can also be used for seasoning.

Planting Fennel

When to Plant

Plant fennel in the spring after the threat of frost has passed. It takes between 60 and 90 days for most fennel varieties to mature.

Selecting a Planting Site

A sunny planting site with good soil drainage is key. Besides planting in the garden, raised beds and containers also are options. Fennel should not be planted in the same area as dill or coriander, as cross-pollination can occur and affect the flavor of the seeds. In addition, be sure to take the fennel variety's mature size into account at planting time, so it doesn't shade nearby plants. Also, it can inhibit the growth of tomatoes and beans, so avoid planting near either of those crops.

Spacing, Depth, and Support

Plant seeds roughly 1/4 to 1/2 inch deep, and plant nursery starts at the same depth they were growing in their previous pot. Plants should be spaced around 6 to 12 inches apart, and they typically won't need a support structure.

Growing Fennel

How to Grow Fennel From Seed

Soak seeds in water for a day or two prior to planting to speed up germination. Fennel seeds direct sown in the garden will germinate in a week or two. Keep the soil evenly moist but not soggy as you wait for germination. Seeds also can be started indoors about four weeks before your last projected frost date in the spring under grow lights. Be sure to gradually acclimate indoor seedlings to outdoor conditions before planting them in the garden after the weather warms.

How to Grow Fennel in Pots

You can easily grow fennel in containers. In fact, this can be a good option to prevent the plant from self-seeding in your garden where you don't want it. The container should be at least 10 inches deep with a similar width, and it should have drainage holes. An unglazed clay container is ideal to allow excess soil moisture to escape through its walls.

Fennel Plant Care


Fennel prefers full sunlight, meaning at least six hours of direct sun on most days. Shady conditions will make it leggy and floppy.


Plant fennel in moist, fertile, well-drained soil. It prefers a slightly acidic soil pH.


Fennel likes evenly moist but not soggy soil. Water whenever the soil feels dry about an inch down, but don’t allow the plant to become waterlogged.

Temperature and Humidity

Fennel is a perennial plant within its growing zones, but gardeners outside of its zones often grow it as an annual. The plant is sensitive to frost and cold temperatures. Plus, hot and dry conditions can cause it to bolt and go to seed. Gardeners in mild climates are sometimes able to plant in the late summer for a fall harvest as long as the temperature remains fairly warm. The plant grows best in temperatures between 60 and 70 degrees Fahrenheit and in moderate humidity levels.


Fennel generally doesn't need fertilizer. But it will appreciate compost worked into the soil at the time of planting, along with a layer of compost added around its base every few months during the growing season.


Fennel plants are self-pollinators.

Harvesting Fennel

Harvest fennel leaves as needed throughout the growing season for fresh use. It's used in both raw and cooked dishes. Frequent harvesting will promote a bushier growth habit and consequently more harvestable foliage. But don't trim off more than a third of the plant at once. Bulbs can be harvested as soon as the base of the stem becomes swollen. Pull up the plants, and store the bulbs unwashed in the refrigerator for up to five days before use.

Pruning and Propagating Fennel


If you wish, you can pinch off flowers as they appear to prevent the plant from going to seed. This keeps the foliage growing and tasting its best for as long as possible. It also stops the plant from freely self-seeding in your garden. However, if you want the seeds for harvesting or self-seeding, allow the flowers to bloom.

Propagating Fennel

Fennel has a long taproot and thus doesn't divide very easily. The better method is to propagate by seeds. This is both an easy and inexpensive way to get new plants, especially if you live where fennel can only be grown as an annual. Here's how:

  1. Watch for seed heads to form on a mature fennel plant at the end of its growing season.

  2. Shake the heads over a sheet or tarp to collect the seeds within.

  3. Spread the seeds in a single layer in a cool, dark, dry spot to fully dry them for a week or two.

  4. Store the seeds in an airtight labeled container, and plant them in the garden the following spring.

Potting and Repotting Fennel

An all-purpose, well-draining potting mix is typically fine for fennel. For container growth, aim to choose a pot that will accommodate the plant's mature size right from the start to avoid having to repot. Fennel doesn't like its roots disturbed. So that means using biodegradable pots for seedlings that can be planted directly in the soil.


If frost is expected in your area, go ahead and harvest the rest of your fennel plant. Otherwise the foliage will likely be damaged or killed. In mild climates, fennel plants can be overwintered for a second growing season, but they usually degrade after that. If unseasonably cold weather is expected in those climates, cover the plants with row covers or another form of protection.

Pests and Plant Diseases

Fennel rarely suffers from serious pest or disease problems, though caterpillars might chew on the leaves. This is best handled simply by picking them off the plants by hand. Most often, they are parsley worm caterpillars, which evolve into black swallowtail butterflies, beneficial pollinators for the garden. You can, therefore, choose to ignore these green caterpillars with black and yellow bands if they're not causing a major issue.

Aphids also can sometimes be an issue, but they can be treated by strong sprays of water to dislodge them. Avoid using chemical pesticides on edible herbs.

In soil with poor drainage, root rot can occur. If you have heavy soil, try a raised garden bed or container to achieve optimal soil conditions.

Benefits of Fennel

Some major benefits of fennel on human health are listed below:

Bone Health

Fennel is rich in vitamins and minerals which help in building and maintaining the structure and strength of bones.

  • Phosphate and calcium present in fennel are essential for bone structure.

  • Zinc and iron are important for collagen production and its maturation.

  • Manganese is required for bone matrix formation.

  • Vitamin K contributes to the modification of bone matrix proteins and improved calcium absorption.

Blood Pressure

Fennel contains calcium, potassium and magnesium which help decrease blood pressure naturally. Potassium plays a major role in dilation and constriction of blood vessels which is the primary mechanism of blood pressure maintenance.

Nitrates that are present in fennel also provide vasoprotection as a result of which, blood pressure is lowered and the heart is protected.

Cardiac Health

Fennel contains vitamin C, potassium, folate, fiber, vitamin B6 and other essential nutrients that are imperative for heart health. The lack of cholesterol in fennel is another added benefit of fennel on the heart.


Fennel contains selenium which is not found in a lot of fruits and vegetables. It improves the liver enzyme function and helps in detoxification of certain cancer-causing compounds. It can greatly reduce inflammation and decrease the growth rate of tumors.

Vitamin C and vitamin A provide antioxidants that protect the healthy cells of the body from damage by free radicals. In addition, the folate present in fennel repairs the DNA and boosts synthesis of healthy DNA.


Fennel can improve the immune response of the body. Selenium that is present in fennel plays a role in stimulating the helper-T cells which are a vital part of the human immune system.


Choline is another component found in fennel. It helps in the maintenance of cell membrane structure, absorption of fat, the transmission of nerve impulses and reduces chronic inflammation.


The fiber content in fennel helps prevent constipation. It promotes a healthy digestive tract. Fennel can aid in the treatment of diarrhea as anethole in fennel is a disinfectant and has antibacterial characteristics.


Fennel is rich in vitamin B6 which plays an important role in energy metabolism. It breaks down nutrients like proteins and carbohydrates into simpler forms that are easily utilized for energy synthesis.

Weight Management

As fennel is rich in fiber, it functions as a bulking agent. It gives you a feeling of fullness as a result of which food intake is greatly reduced.


Fennel naturally contains estrogen that regulates the female reproductive system. Estrogen can also help in determining fertility. A healthy intake of fennel would ensure a well regulated female reproductive system.

Fennel is an emmenagogue, which means it can help in the regulation of the menstrual cycle by regulating the hormonal activity in the body.


Fennel is excellent for healthy, glowing skin. Vitamin C present in fennel is essential for collagen that is the primary constituent for the support of the skin. Moreover, vitamin C is a well-known antioxidant that prevents sun-induced damage to the skin. Using fennel regularly can keep wrinkles away.

Prevents Anemia

Fennel is a rich source of iron and histidine. Both of these constituents are extremely important for the treatment of anemia. Iron is the primary component of hemoglobin and histidine stimulates hemoglobin production.

Improved Brain Function

Fennel has significant amounts of potassium which is an electrolyte. It facilitates the electrical conduction of impulses throughout the body. The brain is a center of electrical conduction and the potassium in fennel boosts this conduction. As a result, brain function improves.

Alleviates Colic

Fennel has antispasmodic activity. Due to this quality, it can help in relaxation of muscles and reduce the discomfort that is associated with colic.

Phytoestrogens are usually used for the treatment of colic and surprisingly, fennel has these heavy molecules naturally. Anethole, which is a constituent of fennel, is a source for these phytoestrogens. Further research is required to investigate this benefit in humans.


  • Fennel leaves can be used fresh or dried as a spice in cooking.

  • The bulb of some varieties is also edible and is usually consumed after cooking.

  • The seeds can be dried and used as a spice.

  • Fennel flowers are edible, and make wonderful garnishes for fish, meat, potato, and tomato dishes.

  • Fennel stems also look wonderful in fresh bouquets.

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