Fennel, Foeniculum vulgare – Cultivation of bulbous fennel

Gardeners who own a greenhouse or have enough space in the house avoid the dangers of direct sowing by growing fennel bulbs under glass from March. In this way, they give the umbelliferae a considerable growth advantage, because the warmth-loving vegetable plant can be sown outdoors from mid-May at the earliest. Peat press pots, which are planted out in spring together with the young fennel plants, are best suited for cultivation, so that the coveted tuber and the sensitive taproot do not have to be touched during this process.

• Sow the fennel seeds in seed trays or peat press pots from mid-April.
• Cover the seeds thinly with substrate and moisten slightly.
• The ideal germination temperature is between 20° and 22° Celsius.

As soon as the cotyledons appear, it is essential to place the culture vessels in a cooler and brighter place, at a maximum of 16° Celsius. This measure prevents the bulbous fennel from developing too long root necks at this early stage, which means that the hope of compact, robust bulbs is fading. After another 5 weeks, the early young plants can be planted out in the bed. Fennel is unsuitable for pot culture.

Proven spring varieties

The following fennel varieties have proven themselves in practice for early sowing:

• Argo: resistant to bolting even with early sowing.
• Acts: Tough, Traditionelle Luck.
• Bolognese: suitable for early and late sowing.
• Montavano: image attachment, round tuber.
• Selma: bolt-resistant with thick tubers and firm foliage.
• Sperlings Cantino: robust, bolt-resistant variety.
• Zefa Fino: classic variety for early and subsequent cultivation

location

In order for fennel to be able to fully develop its multifaceted talents, it needs a warm and sheltered location, as the Mediterranean cultivated plant knows from its homeland.

• Full sun to sunny and sheltered from the wind.
• Moderately dry, loose and humus rich soil.
• As a medium feeder, fennel needs a nutrient-rich soil.

The growth of tuberous fennel is beneficial if cauliflower, potatoes, radishes or lettuce were grown at the chosen location in the previous year. In addition, legumes leave favorable soil conditions when followed by fennel.

direct sowing

If the hobby gardener does not have any options for growing under glass, he can sow directly at a suitable location from the end of May.

• Loosen the soil thoroughly and clean of weeds, roots or stones.
• Work well-rotted garden compost and some horn meal into the soil.
• Make 2 cm deep furrows with the spade and sow the seeds 25 cm apart.
• Plant several rows of Foeniculum vulgare 40 cm apart

After the soil has been sprayed with water, it should be covered with a warm fleece or foil for the coming weeks, as fennel tends to sprout when exposed to unexpected cold. Likewise, a constant alternation between dry and wet promotes the shooting of the umbelliferous plants. On the other hand, if the plants are under foil, this undesirable effect can be kept under control, at least to some extent.

The experienced hobby gardener sows autumn fennel between June 15th and July 5th. In this case, of course, protection against the cold can be dispensed with. In addition, the late varieties hardly tend to shoot. The gardener, on the other hand, is never spared the regular weeding.

Plant early fennel

Fennel bulbs grown under glass are mature enough from the middle/end of May that they can be planted out. Young plants with 3 to 4 leaves have the best chance of a successful culture. The same planting and row spacing applies as for direct sowing. Anyone who has decided to use peat press pots for sowing now benefits from the fact that the sensitive taproots do not have to be potted out.

• Only dig the planting holes so deep that the bulb base is above the ground.
• In this way, it is prevented that only elongated tuber fennel develops.
• Before planting, enrich the excavation with garden compost.

The last fennel plants should be in the bed by mid-August at the latest so that they mature in time before the first frost.

maintenance

Fennel requires regular attention so that the tender, white onions develop as desired, plump, round and crisp with the unique aroma reminiscent of aniseed.

• Pull weeds every 2 to 3 days.
• Keep moderately moist without causing waterlogging.
• A mulch layer of straw or grass clippings keeps the soil moist in summer.
• Bark mulch is not suitable because the material removes nutrients from the soil.

Gardeners who prefer a combination of organic and classic fertilizers, apply 3 liters of compost per square meter and a maximum of 35 grams of calcium ammonium nitrate (highly concentrated nitrogen fertilizer) per square meter before planting as part of the soil preparation. After 3 weeks, fertilize with 25 grams of calcium ammonium nitrate per square meter of bed area.

If a previous soil analysis has shown that the garden soil has a high phosphorus and potassium content, the first application of calcium ammonium nitrate is reduced from 35 to 25 grams per m².

pile up

The experienced gardener always keeps an eye on the tubers. When they reach around 3 cm in diameter, while white bulbous buds form at the base, it’s time to mound the plants. This measure should be taken no later than 2 weeks before harvest, otherwise the fennel bulbs will discolour, which will affect the aroma.

• Work the soil so that it has a fine, crumbly consistency.
• Then carefully pull the fennel with the hoe.
• The succulent leaf stalks must be covered, while the green parts of the leaf remain uncovered.

Piling up is rewarded with white, crunchy-sweet fennel bulbs. They are ready to harvest when they reach the size of a fist. If the tubers get too big, they lose their tenderness.
Field-tested summer and autumn varieties

• Finale: juicy, aromatic, well suited for the grill.
• Heracles: larger yields when sown later.
• Match: convinces with top quality.
• Orion F 1: a professional all-season hybrid variety.
• Pollux: mediocre yield, but very robust and round.
• Rondo F 1: bolt-resistant with beautiful, round tubers
• Rudy: new autumn variety with a long harvest time.
• Sirio: best quality when sown in July.

The hobby gardener also benefits from the results of numerous trials for commercial cultivation. Test series have repeatedly shown that autumn varieties tend to bolt much less than early fennel varieties.

What does shooting mean?

Foeniculum vulgare is one of the long-day plants. Behind this name lies the property of the plant that its green shoots shoot up and bloom when the days get longer in spring. On the other hand, this process is not desirable, as it takes place at the expense of the coveted fennel bulbs, because the plant invests all its energy in the growth of the shoots. The harvest result is correspondingly devastating in puny, flattened tubers that lack any aroma. The knowledgeable hobby gardener prevents this dilemma:

• Preferably plant fennel varieties that have proven to be bolt resistant.
• Do not sow or plant before mid/end of June.
• In principle, settle the tuberous fennel in warm, sheltered locations.

Happy the garden friends who cultivate their vegetable beds in the mild wine-growing climate. If you are not granted this privilege, you can use the already mentioned warming effect of a foil cover or plant your fennel bulb in a raised bed.

This would also explain why late fennel varieties only very rarely tend to bolt. When the hobby gardener starts sowing or planting, the days are already beginning to shorten.

harvest and storage

As a Mediterranean plant, fennel is extremely sensitive to cold. Consequently, the entire crop should be brought in by the first frost. Roots and leaves are removed from the tuber and ideally prepared fresh from the garden. Fresh consumption is not absolutely necessary, however, because fennel has a limited shelf life.

• Store in the vegetable compartment of the refrigerator for approx. 3 weeks in a damp cloth.
• Pack the tubers and roots in moist sand and store in the cellar for 6 to 8 weeks.
• Freeze in portions in the freezer.

Incidentally, the green parts of plants are far too good to dispose of in the compost. They refine soups, salads and meat dishes in the kitchen.

diseases and pests

Young, tender Foeniculum vulgare are among the favorite foods of slugs. The experienced hobby gardener prevents this danger at an early stage:

• Create a moving barrier around the bed made of sharp material such as chippings or shavings.
• Scattered coffee grounds are poisonous to snails and cause them to turn back.
• Protect individual plants with a snail collar.
• Always water the fennel bulb early in the morning so that it dries overnight.
• Build a snail fence around the vegetable patch and set up beer traps.

Ground beetles are important predators of slugs. If you find suitable retreats in a garden, they remain in the area and hunt for the pests’ eggs at night. An upside-down flower pot filled with wood wool invites the beneficial insects to linger.

Aphids
These tiny parasites hardly spare a plant in the kitchen or ornamental garden. With the help of their stinging and sucking mouthparts, they rob the fennel of the life force while they multiply explosively. Since the use of chemical preparations in the vegetable patch is out of the question, the settlement of beneficial insects that are after aphids is a good idea:

• lacewing larvae
• ladybug
• parasitic wasps

The insects are specifically bred and are available in specialist shops. They only destroy the aphids without harming the plants.

Conclusion
As an indispensable ingredient in Mediterranean cuisine, the tuber fennel has firmly established itself in the gardener’s vegetable patch. In contrast to other crops, cultivation is a bit more demanding; With the help of practical tips, sufficient attention and a little skill, however, it can be easily mastered. Choosing the right variety in combination with growing under glass paves the way to successful cultivation. The result is tender, white fennel bulbs, which provide a healthy variety in the menu.