How to Grow Fennel

Fennel is found in many gardens and is quite easy to grow. So easy, in fact, that it has gone wild in many place throughout the world. In some places it is even considered an invasive species. Even so, it likes mild climates best, with non-acidic, well-drained loams rich in limestones or chalk, in full sun. It is a perennial that can be grown from seed or from root division. But in northern climes is generally treated as an annual.

Fennel in the Garden

To grow fennel, plant directly from seed, fairly thickly, in rows two or three feet apart (well-composted raised beds are best). Then cover lightly (about 1/4 inch). When plants come up, they can be thinned to stand six to twelve inches apart in the row. Seeds can also be started in-doors and transplanted when they reach about four inches. Fennel has a long tap root so disturbing roots can cause the plants to bolt. Direct seeding is best, especially when planting for the bulb.

Should not be planted near bush beans, tomatoes or caraway.1 It may be wise to stake plants in windy areas, as they can be blown over.

Make certain that plants have sufficient moisture during the growing season. They may be dressed with compost. As with most garden plants, weeding around them is a good idea.

Fennel seeds can be harvested during the growing season. The seeds can be taken when they turn a light brown. Cut the umbels in the morning to minimize seeds falling off. Dry the seeds in the sun before storing in a jar. This prevents them from molding from residual moisture.

The bulbs are also good for eating and can be picked for use as soon as they form. (Simply pull the entire plant and remove the stems and roots.) They can get as large as a baseball and can still be used at that point in their growth. When harvesting entire plants, but not the whole crop, use it as an opportunity for thinning, removing larger plants to allow smaller plants to more fully develop. During the first year, fennel will grow to three to four feet in height.

Plants can bolt when planted in the spring. In this case they form the flower head (umbels) and make seed without ever forming a bulb at the base. This is okay if the gardener is only planning on harvesting the seed. Fennel becomes mature in about 80 days, so it can be planted later, in early summer, when it is less likely to bolt. Also, adding plenty of nitrogen to the soil will help.2

Fennel is a hardy plant and will continue to grow, even after several hard frosts, so it is not vital that the plant be harvested precipitately in the face of the weather. It will easily over-winter in tropical climates. In most temperate places it can over-winter if protected by a deep layer of mulch in the late autumn.

Fennel Varieties

Florence Fennel, also called Finocchio (common fennel), is generally planted for the bulb (or swollen leaf base). It has finely divided, needle-like foliage resembling dill. The color is a light apple green. It comes in many varieties. One which produces early is called Romano Precoce. A bolt resistant variety is Fennel di Firenza. Fennel di Sicilia is larger than most varieties. For a stronger liquorice flavor try Fennel Mantovano3.

Sweet Fennel is the variety that is generally planted for the seeds, but the leaves and stalks may also be consumed. The stems (like those of Florence Fennel are solid). It grows from four to six feet in height. Production in the first year is not prolific. (If too many flower heads are left on the plant, the plants tend to wither.)4 Some varieties of sweet fennel will not bulb up.

Bronze Fennel can be used in place of Florence fennel or sweet fennel in recipes. The main difference is the coloration of the leaves. The seeds are often used to flavor sausage. Certain types of butterfly, especially the anise swallowtail, are particularly attracted to fennel.

<< Health Benefits of Fennel | Cooking with Fennel >>

  1. Encyclopedia of Organic Gardening, by Editors of Organic Gardening Magazine (1978) (p 359)
  2. Grow Better Veggies on Growing Fennel
  3. GourmetSeed Fennel Varieties
  4. Taylor's Guide to Vegetables and Herbs, (1987) (p 425)


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