Cultivation of fennel: a simple and complete practical guide

How to grow fennel: in pots, in the vegetable garden or in hydroponics

Fennel is a plant suitable for all seasons due to its lightness and its very tasty aroma. Follow our guide and you will discover all the secrets to always have excellent and very aromatic fresh fennel at home directly from your vegetable garden or from your hydroponic garden.


1. The Fennel: a bit of history and main characteristics
2. The climate and ideal conditions for growing fennel.
3. How to grow fennel: from sowing to germination.
4. Growth of fennel
5. Grow fennel in hydroponics
6. Take care of the fennel plant
7. Fennel pests and potential diseases
8. Pet plants for fennel
9. Preservation and harvesting of fennel
10. Cooking with Fennel

Let's see step by step how to grow fennel and take care of it.

1. Fennel: a bit of history and main characteristics

Like many herbs and aromatic plants commonly used in cooking, fennel (originally called Foeniculum vulgare) is typical of Mediterranean countries and is also used for the preparation and embellishment of many dishes. Greece, in particular, traditionally has a very close relationship with fennel; Suffice it to say that the Greek word with which the fennel plant is identified is "máratho", or marathon. This is because the "Battle of the Marathon" took place in a fennel field, giving life to the current concept of a marathon.
It is a plant with a delicate, slightly sweet scent, enriched by a pleasant non-invasive touch of anise: the fennel leaves, which resemble fine and delicate feathers, are very reminiscent of those of dill and are ideal for seasoning dishes based on white meat and fish.

We can eat every part of the fennel, both the central bulb, harder and more resistant and rich in vitamins, and the leaves.
Fennel is an ideal aromatic herb in cooking and is very versatile, because the main bulb of the plant can be cooked and served like an onion: caramelized, roasted, sauteed or used for the preparation of soups and other dishes. Green leaves can be added to various dishes as a garnish, for example cut into small pieces and sprinkled on fish, potatoes and creamy dishes; or - alternatively - dried and stored for use as needed.
The fennel plant, due to its diuretic and purifying properties, is also commonly used for the preparation of herbal teas and infusions.

If you want to experiment in the cultivation of fennel, have it always available at home and close at hand, or start a small professional cultivation and be able to resell fennel on the market, thus transforming it into a source of income, the advice is to carefully evaluate the opportunity to start a hydroponics. In general, in fact, it is preferable to grow fennel with hydroponic methods, both because it requires less space than in open fields, and because it is easier to manage and maintain a crop in water than the necessary care it requires. a traditional type of crop.
In this guide you will find information on both the traditional cultivation method, directly in the ground (therefore in the open field or inside a greenhouse) and with the hydroponic method, with useful and practical advice for those who want to start a soilless cultivation that allows save time and energy and cultivate even if you don't have land available.

2. The climate and ideal conditions for growing fennel.

Like all plants of Mediterranean origin, fennel also needs a mild climate, therefore neither too hot nor too cold; The ideal temperature for fennel to grow and live well and healthy should never exceed 30 degrees, but, more than any other aspect, it should never be subjected to frosts, an extremely harmful condition for this type of plant. The ideal period for its cultivation is spring and summer, therefore the recommended period for sowing is from March to July, in order to prevent the plant from growing and reaching maturity during the coldest period of the year.
Before sowing the fennel, it is advisable to work the soil in which you are going to lay the seeds, taking care to aerate the soil and fertilize it correctly, to better prepare it before sowing.

3. How to grow fennel: from sowing to germination.

The simplest and safest method to grow fennel is to start from the seed, especially if you have decided for the first time to start a local fennel crop: to facilitate the germination process, we recommend using a fairly deep seedbed. Regardless of the type of container used, it is essential to provide and spread a layer of gravel and clay on the bottom, to promote drainage and avoid dangerous stagnation of water, then cover with an abundant layer of medium-soft soil and enrich it with fertilizer.

If, on the other hand, you already feel confident enough, you can place the seeds directly in the ground, at a depth of about 5cm, preferably at a time when the soil is warm and able to favor germination, a process that takes place within a maximum period of 8. - 12 days (usually occurs after 7-10 days). It is good to know that to make a gram you need about 200-300 seeds, a number that will also change depending on the variety of fennel you have selected and chosen to grow.

Once germination has been carried out, if a special seedbed or container has been used for this phase, the seedlings can be transplanted in the open field or in a greenhouse in winter, as long as they are placed at a distance of 30-45 centimeters from each other.

4. Growth of fennel

The cultivation of fennel is quite simple, since, unlike other vegetables, it does not require special care, as long as you follow some precautions. Fennel belongs to the same family as carrots, parsley, and dill, and the fruits of fennel plants are what we mistakenly call seeds.
If you decide to grow fennel in the traditional way - that is, in the field or in the garden, in pots or in wooden boxes - it is important that they are placed in an area in full sun, that the soil is well drained and rich in organic matter. The fennel plant begins to bloom after a few weeks and at the same time produces its typical seeds, which can be collected or left on the plant; this can be used for re-sowing.

5. Grow fennel in hydroponics

As with all other types of plants grown with hydroponic methods and systems, fennel also needs its ideal conditions to grow vigorous and healthy.
The electrical conductivity (or EC) - which can be measured with a conductivity meter - must be between 1 and 1.4, the pH - which can be measured with a pH meter or with an instrument that measures both EC and PH - must be between 5.5 and 7 , 0, preferably staying between 6.0 and 7.0 (between acidic and neutral on the scale).
The temperature should be between 15 and 20 degrees Celsius, always remembering that, in general, the fennel plant tolerates both heat and cold quite well, but not frost and excessively low temperatures.

As seen above, the fennel plant prefers low electrical conductivity (low EC) and moderate pH. It is also good to remember that this plant is rarely subject to parasites, as long as it is properly treated, even if aphid infestations could compromise or partially damage the crop.

Fennel, in general, does not present germination problems and is in fact considered a particularly flowering plant, with a rooting rate ranging from 60% to 90%. It should be remembered that the seeds take 10-14 days to germinate and are ready for sowing after 3-5 weeks. The bulbs, once grown, can be harvested when desired, but it is important to keep in mind that the ideal weight of fennel, which is normally found on the market, fluctuates between about 200 and 400 grams. It takes 6 to 8 weeks to reach this weight.

Since the seed is relatively slow to germinate, it is advisable to sow fennel in early spring; To grow well and healthily, the plant will need full sun, regardless of the type of substrate you choose. Also, since the plants grow fast, it is recommended to sow every two weeks, so that you can periodically harvest and always have fennel available.

Fennel propagates very well from seed, but it can also propagate from the root and corolla. It can also be planted in autumn: it is possible to sow indoors, wait for the plants to be at least 8-10 centimeters high, and then transfer them to a larger greenhouse. Fennel is a fairly flexible plant that easily adapts to different contexts: it can in fact be grown in a container or pot, with the use of hydroponic systems.

6. Take care of the fennel plant

As anticipated above, among the useful treatments to be carried out during the growth phase of the fennel plant, remember to provide with regular, monthly fertilizations (at most every two months), make sure that the soil is always moist (especially in the hottest periods) and water regularly and abundantly, taking care not to overdo it to avoid dangerous stagnation of water. Just to be safe, remember to let the soil dry almost completely between waterings, then water abundantly. Finally, even if it is not a vegetable particularly subject to the aggression of parasites, it is always advisable to carefully observe the possible attack of aphids and to promptly provide the appropriate products.

Here are some tips for fennel care during the growing season.

  • Watering: Until well established, growing fennel should be watered regularly to ensure it receives an even amount of moisture. Once the plants are large and healthy, they can tolerate some dryness.
  • Weeding: Use mulch to keep weeds at bay.
  • Fertilization: Apply a layer of compost around the base of your growing fennel plants at least once a month during the growing season. Use organic organic fertilizers such as BioMagno Grow with a high content of nitrogen, phosphorus and potassium. Also giving the correct amount of calcium during flowering will have positive effects not only on the final harvest phase, but also on the shelf life in the refrigerator after harvest.
  • Pruning: Remove the flowers to prevent the plants from self-seeding if you don't want the fennel to appear in the same spot next year. Otherwise, let the buds bloom as they will attract pollinators.

7. Fennel pests and potential diseases

If you decide to plant fennel outdoors, remember that this plant is harmful to most crops, as it attracts the syphilis fly and tachinid fly, bees, butterflies and birds; Instead, it is recommended to encourage the presence of ladybugs, which feed on other parasites that are potentially dangerous for plant life.
Consequently, the only plant that will grow harmless near fennel is dill; For this reason it is essential to avoid planting fennel next to any other plant, as it could inhibit their growth or even cause their death.


You may find caterpillars chewing on fennel tops. These are likely swallowtail butterfly caterpillars. They like to eat plants from the same family (carrots, dill, parsley, etc.).


Virtually no plants are safe from aphids. Remove the small suckers from the fennel and sprinkle with neem oil.

Downy mildew

Mold is caused by a parasite that causes yellow and white spots to appear on the tops of the leaves, with white, powdery mold on the underside. Make sure your plants get plenty of air circulation, water in the morning, destroy infected plants and use a copper spray to control it.

White mold

Powdery mildew is caused by a fungus that makes plants look like they are dusted with flour. Destroy infected plants and treat them with a fungicide such as Muskaria by Agrobacterias..

Bulbs that do not form

Another problem that can occur with fennel is the absence of bulbs. First, check your seed packet and verify that you have planted a variety of bulbs. The lack of bulb can also be due to heat. Like other heat sensitive plants, fennel can start developing bulbs at high temperatures. Once the plant begins to bloom, it will no longer use its energy to grow a bulb.

8. Pet plants for fennel

Plant the fennel next to the dill, cucumber and nasturtium.

Do not plant fennel near:

  • Tomatoes
  • Beans
  • Coriander
  • Absinthe

9. Preservation and harvesting of fennel

You can eat almost any part of the fennel plant from seed to bulb. The harvest takes place after about 2 months. You can harvest the fronds once the plant has established by cutting the buds to encourage growth. Collect the seeds once the flowers have wilted and turned brown. Then collect the bulb once the plant is ripe.

Fennel bulbs can be kept in the refrigerator for about a week. To keep the fronds fresh, separate them from the bulb and store them in a separate container.

If you are interested in saving seeds from your fennel plant, wrap them in cheesecloth towards the end of the season to harvest the seeds before they fall to the ground.

10. Cooking with Fennel: Ideas and other recipes

One of the hardest parts of gardening doesn't seem like a problem in itself: when it's time to harvest, it's a challenge figuring out how to use it all without letting it go to waste. Not sure how to use the fennel you have grown?

Here are some suggestions:

  • Eat it raw. Chew sliced ??raw fennel instead of celery. It tastes crunchy and fresh and a delicious snack if you don't hate the strong anise flavor.
  • Saute or cook the sliced ??fennel to soften the flavor.
  • Cut the fennel tops and add them to the salad dressing or use as a side dish.
  • Combine fennel with shellfish.
  • Fennel also goes well with other meats. The refreshing flavor balances the flavor of the meat.

Here are some fennel recipes worth trying:

  • Caramelized Fennel - One of our favorite ways to enjoy fennel.
  • Roasted Carrots and Fennel - Unsurprisingly, these two vegetables from the same family go well together. It is a tasty side dish.
  • Roasted Cod with Orange and Fennel - You must seriously try pairing fennel with citrus and fish. It is a magical combination.
  • A Roast Chicken with Fennel - Fennel is not only great with fish, but also goes well with chicken.
  • Fennel Risotto - A little lemon cheers up this risotto dish that's worth putting on the menu for your next dinner.

Grow this sweet, light, dietary and very tasty plant with us!

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