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How to Plant and Grow Florence Fennel

Florence fennel in the kitchen

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All parts of Florence fennel can be eaten. The bulb can be prepared like celery; it can be eaten raw or cooked. The leaves and tenderest branches can be used in soups and salads. The seeds can be used as a flavoring in baked goods.

Florence fennel requires a long, cool growing season, about 100 days. Fennel can tolerate cold but is killed by frosts. Conversely, temperatures too high cause the plant to bolt.

Sow seeds indoors 4 to 6 weeks before the last frost in spring. Set seedlings in the garden shortly after the last frost. Seedlings should be about 3 to 4 inches tall or more at transplant time. Sow seeds directly in the garden when the soil warms to 68° (16°C).

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Florence fennel will grow in most soils, but for quick growth and thick, tender stalks, grow in humus-rich, well-drained soil. Monthly side-dressings of well-rotted manure or waterings with manure tea will help plants produce tender, thick-fleshed bulbs, and stems.

Bulbous stems will be fully grown at 90 to 120 days; do not delay harvest past this time. Leaves and tender branches can be used as soon as the plant is about 18 inches (45cm) tall.

Grow Florence fennel
Florence fennel is grown for its bulbous stem

Florence fennel is a cool-weather perennial grown as an annual. Florence fennel or finocchio is grown primarily for its bulbous base and leaf stalks which are used as vegetables. Fennel is a stocky plant that can grow to 24 inches (61cm) tall and looks something like celery with fleshy stalks and feathery leaves.

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A taller cultivar of fennel known as common or sweet fennel is grown for its leaves and seeds which are used as herbal seasonings. Fennel produces a flat-topped cluster of small, golden flowers. Both Florence fennel and common fennel are members of the parsley family.

Florence fennel seedlings
Florence fennel seedlings

Florence fennel planting details

  • Sowing depth: ¼ inch (6mm)
  • Space between plants after thinning: 10-12 inches (10-15cm)
  • Days to sprout: 7-14
  • Days to harvest: 90-115
  • Storage period: 7 days
  • Suggested varieties: Hearld, Zefa Fino, Rudy, Trieste

Florence fennel growing quick tips

  • Fennel can be sown in the garden as early as 2 to 3 weeks before the average last frost date in spring.
  • Florence fennel, which is grown for its bulbous stalk, requires 90 to 115 frost-free days to reach harvest.
  • For autumn crops sow fennel in mid-to-late summer.
  • Florence fennel yield: plant 5 Florence fennel plants for each household member.
Florence fennel is a cool-weather perennial grown as an annual.

Where to plant Florence fennel

  • Grow Florence fennel in full sun.
  • Plant Florence fennel in well-drained soil rich in organic matter.
  • Prepare the bed in advance by working with aged compost.
  • Fennel prefers a soil pH of 5.5 to 6.8.

Florence fennel planting time

  • Florence fennel is a cool-weather perennial grown as an annual.
  • Florence fennel can be sown in the garden as early as 2 to 3 weeks before the average last frost date in spring.
  • Seeds germinate best at 60°F (17°C).
  • Florence fennel will tolerate heat and cold but does best when it comes to maturity in cool weather.
  • Florence fennel requires 90 to 115 frost-free days to reach harvest.
  • For an autumn crop sow fennel in mid-to-late summer.

Florence Fennel seed sowing dates

(These dates are for the Northern Hemisphere)

Average date of the last frostPlanting dates
Jan. 30Jan. 1-Mar. 1
Feb. 8Jan. 1-Mar. 1
Feb. 18Jan. 15-Mar. 1
Feb. 28Feb. 1-Mar. 1
Mar. 10Feb. 15-Mar. 15
Mar. 20Mar. 1-Apr. 1
Mar. 30Mar. 10-Apr. 10
Apr. 10Mar. 15-Apr. 15
Apr. 20Mar. 25-Apr. 15
Apr. 30Apr. 1-May 1
May 10Apr. 15-May 15
May 20May 1-30
May 30May 1-30
June 10May 15-June 1
 Florence fennel at harvest time
Florence fennel at harvest time

Planting and spacing Florence fennel

  • Sow fennel seed a ¼ inch deep 4 to 6 inches (10-15cm) apart.
  • Thin successful seedlings to 12 inches (30cm) apart.
  • Space rows 24 to 36 inches (61-91cm) apart.

Florence fennel companion plants

  • Grow Florence fennel with mints and members of the mint family.

Container growing Florence fennel

  • Florence fennel will grow in a 6-inch (15cm) pot; in larger containers grow Florence fennel on 8-inch (20cm) centers.
  • Spring plantings will not produce a large bulb.
  • Plant in fall so that the plant comes to maturity in cool weather.
Young Florence fennels
Young Florence fennels

Water and feeding Florence fennel

  • Keep Florence fennel on the dry side; the soil should be evenly moist but not wet.
  • Mulch to retain soil moisture in hot regions.
  • Prepare planting beds with aged compost.
  • Side dress fennel with aged compost at midseason.

Florence fennel care

  • Blanch the lower stems of Florence fennel when the bulbous base grows to the size of an egg; do this by mulching up around the bulb–the bulb will be more tender and sweet at harvest.
  • Remove seed stalks to increase the production of stems and bulbs.
  • Fennel will self-seed if left unattended.

Florence fennel pests and diseases

  • Fennel may be attacked by the parsley caterpillar. Remove it by hand. Generally, Florence fennel has no other serious pest problems.
  • Fennel has no serious disease problems.

Harvesting Florence fennel

  • Florence fennel’s bulbous stalk can be harvested when it is 3 inches (7cm) or more in diameter.
  • Cut the whole stalk like celery just below the point where individual stalks join together.
  • Cut leaves as needed once they have reached 18 inches (45cm) tall.
  • Florence fennel will be ready for harvest 90 to 115 days after sowing.
  • Common fennel sprigs can be cut for flavoring once the plant is established.

Storing and preserving Florence fennel

  • Florence fennel is best eaten fresh.
  • Florence fennel will keep in the refrigerator for up to 1 week or in a cold moist place for 2 to 3 months.
  • Stalks can be frozen or dried.
  • Fennel leaves can be frozen or dried as herbs; dried leaves should be kept in an airtight container.

Florence fennel varieties to grow

  • Varieties. ‘Hearld’ for spring planting. ‘Zefa Fino’, ‘Rudy’, and ‘Trieste’ have large, flavorful bulbs.

About Florence fennel

  • Common name. Fennel, Florence fennel, finocchio, fenucchi
  • Botanical name. Foeniculum vulgare dulce
  • Origin. Mediterranean

Relared articles:

How to Plant and Grow Florence Fennel

Four Tasty Ways to Cook and Serve Florence Fennel

How to Grow Common Sweet Fennel

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Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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