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How to Grow Florence Fennel

Grow Florence fennelFlorence fennel is a cool-weather perennial grown as an annual. 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.

Description. 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. 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.

Yield. Plant 5 Florence fennel plants for each household member.

Florence fennel top leavesPlanting Florence Fennel

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

Planting time. Florence fennel is a cool-weather perennial grown as an annual. 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). Fennel will tolerate heat and cold but does best when it comes to maturity in cool weather. Fennel requires 90 to 115 frost-free days to reach harvest. For an autumn crop sow fennel in mid- to late summer.

Planting and spacing. 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.

Companion plants. Mints and members of the mint family.

Container growing. 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.

Florence fennel in garden rowFlorence Fennel Care

Water and feeding. Keep 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.

Care. Blanch the lower stems 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.

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

Diseases. Fennel has no serious disease problems.

Florence fennel harvestHarvesting and Storing Florence Fennel

Harvest. 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. 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.

Common name. Fennel, Florence fennel, finocchio, fenucchi

Botanical name. Foeniculum vulgare dulce

Origin. Mediterranean


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  1. I planted my Florence fennel seed waaaay back in March of 2013. It is now late October of 2013.
    All I got from my seed this summer was some pollen and seed on skinny tall stalks….and that’s about it. Now that cool weather has returned the plants have begun to grow again on their skinny stalks, and I wonder if I can expect the plants to fill out and produce a bulb heer in the late fall or if I’m just wasting space. Thanks if you reply.

    • For best results, grow Florence fennel like you would celery: cool, even-temperatures are best (4 months of cool weather without frost is optimal). Planting beds loaded with humus and compost is necessary to keep the soil moisture content high enough for good bulb development. Optimum pH is 6.0. Florence fennel wants nutrient rich soil–add compost as a sidedressing after preparing beds with compost and well-aged manure. Add bonemeal to aide root development. Sow seed a half-inch deep and 18 inches apart; thin to stand 6 inches apart. When plants are a foot high, draw the soil up around the bulbs. A good growing strategy is to start seed indoors in January or February for planting into the garden 10 weeks later–this will allow for bulb development during the cool spring–or grow outdoors in winter in a cold frame. If the weather is warm during the growing season, use a heavy mulch around plants to slow soil moisture evaporation. Keep the soil evenly moist–not too wet, never let it dry out. (Florence fennel also called finnochio (Foeniculum vulgare dulce) has leaves two to three feet tall arising from a thickened stalk or bulbous enlargement made by the overlapping thickened stems. Florence fennel is grown as an an annual in much of the United States but can be grown as a perennial in warmer regions–which may well include Dallas.)

    • Run your hand down the flowering stalk (seed stalk) to the base of the plant–where the stalk emerges from the fleshy bulb (that bulb is actually an enlarged stem). Cut where the flowering stalk emerges from the bulb or base of the plant.

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