[Skip to Content]
University of Illinois Extension
Herb Gardening

Fennel

Fennel

Foeniculum vulgare

Annual

Description

There are two types of fennel.  One is treated as an herb (herb fennel – Foeniculum vulgare) and one that is treated like a bulb type vegetable (Florence fennel or Finocchio – Foeniculum vulgare var. dulce).  The herb type grows 3-5 feet tall with fine textured foliage resembling dill.  Flat topped clusters of yellow flowers appear in late summer.  Stems, leaves and seeds of this type of fennel are harvested and used.  Florence fennel is shorter with darker green foliage and is grown for its large, flat thick rosette of petioles at the base often referred to as a “bulb.”  Both forms have an anise or licorice flavor.

Culture

Both forms of fennel are grown from seed. Both prefer a full sun location in soil that is well prepared with organic matter. This is especially important when growing Florence fennel as it prefers uniformly moist soil to develop the best “bulb.”  Herb fennel is best direct sown in the garden in the spring after frost is past. It does not transplant well due to its tap root structure.

Florence fennel is also direct sown into the garden but seeding is best done from mid-June to July.  This is done to allow the crop to develop during the cooler, shorter days of late summer and early fall.  If planted earlier, long, hot days of summer result in plants bolting (flowering) thus reducing the quality of the “bulb.”  Another important consideration for Florence fennel is maintaining uniform soil moisture.  If soils are allowed to dry out, it will result in bolting and affect bulb quality.  When “bulbs” start to swell and become the size of an egg, push soil around the “bulb.”  This will produce a paler and tenderer “bulb."   This is a blanching process that is similar to what is done with leek.  

Harvesting

Herb fennel can be harvested as needed by cutting away the feathery foliage. If seed is desired, allow the plant to flower and when the flower heads turn brown the plant can be cut, place in a paper bag and hung in a cool, well-ventilated area to dry.  Seeds will drop down into the bag and can then be cleaned and stored.  Foliage can also be air dried and stored for later use.  Florence fennel can be harvested when the “bulbs” are about the size of tennis balls by digging the “bulb” and cutting off the root and cutting back the top.  “Bulbs” can then be stored in a cool location for several weeks.   

Uses

Herb fennel is used in fish dishes, soup and stews and fennel seed is used in sausage.  Fennel bulbs are used raw in salads or steamed.

Popular Varieties

Herb Fennel Types

  • Sweet Fennel – Standard variety for fresh and dry leaf production.
  • ‘Purpureum’ – A bronze leaf type. It is used as an ornamental.
  • ‘Rubrum’ – A deep bronze to red leaf type.  Also is used as an ornamental.

Florence Fennel Types

  • ‘Rhondo’ – Uniform round bulbs, quick to mature.
  • ‘Victoria’ – Vigorous type with grater resistance to bolting.
  • ‘Cantino’ – A very slow to bolt variety good for early planting.
  • ‘Mantavo’ – Good yield in  slow bolting variety.

« Back to the Herb Directory