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How to Grow: Florence Fennel
Learn how to grow Florence fennel including information on varieties.
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Although listed as an herb, I think of Florence or bulbing fennel (Foeniculum vulgare azoricum) as a vegetable. I’ve made a meal out of a fennel bulb. Once you get hooked on the licorice flavor of fennel and the juicy, crunchy texture, you’ll be growing these 3-inch wide bulbs for grilling, steaming, or roasting. No Easter meal would be complete in my mother’s house growing up without a marinaded fennel salad.
There is also the perennial herb fennel (F. vulgae dulce) that’s grown for it’s decorative and tasty leaves. But Florence fennel is grown for its swollen bulb at the base of the plant, and that’s one I’d like to talk about.
When to Plant
Plant fennel after all danger of frost has passed– May in our region. They form bulbs best during periods of cool weather. If it gets too hot, the plant will bolt (send up a flower stalk) and the bulbs will be small and woody tasting. To get a jump on the season, start seed indoors 3 weeks before the last frost. Fennel seedlings don’t like to be transplanted, so grow seedlings in peat, coir, or cow pots that can be planted directly in the soil with the seedling. These pots will decompose over time.
Where to Plant
Plant fennel in full sun on well drained soil. Because of its taproot, plant on 8-inch tall raised beds so the roots can grow deeply without obstruction. Fennel only grows 1- to 2-feet tall and wide, so makes an excellent container herb and an attractive plant in the flower garden.
How to Plant
Amend the raised bed with compost before planting and remove any large sticks or debris. Sows seeds 4 inches apart in rows spaced 18 inches apart. Thin seeds, or transplant seedlings, to 8 inches apart when plants are 4 inches tall.
Care and Maintenance
The longer you can keep the soil and air cool and moist, the larger the potential bulb will grow. Fennel can take up to 3 months to be ready for harvest. Keep the bed weed free and watered regularly. Be careful not to disturb the roots or it will stimulate the plant to bolt early. Once established, mulch with bed with a layer of straw or untreated grass clippings to preserve water and keep the soil cool. Cut off any flower stalks that form to encourage a larger bulb.
Mulch around the bulb with soil when it’s 2 inches in diameter to blanch (block the light) it. Blanched bulbs are white colored and more tender. Fennel has few pests other than the larvae form of the black swallowtail butterfly. Handpick these caterpillars if they become too plentiful in the garden, otherwise enjoy the butterflies once they form.
Harvest
Harvest bulbs when they’re 3 inches in diameter, before they flower, by pulling the whole plant out of the ground. Cut off the roots and trim the stems and leaves 2 inches above the bulb and either save for eating or compost. The stems and leaves can also be harvested anytime to be used in salads and soups, but they have a stronger licorice flavor.
Additional Information
‘Perfection’ is an early maturing variety that’s slow to bolt. ‘Orion Hybrid’ is a new high yielding variety.
Text excepted from the Northeast Vegetable and Fruit Gardening book.
Podcast Transcript
Easter Sunday at my Italian mother’s house wasn’t complete without her traditional sausage pie and finocchio salad. Being a vegetarian I don’t eat the rich tasting sausage pie anymore, but I still love finocchio or Florence fennel. Florence fennel is a cultivated version of the wild fennel plants that are native to the Mediterranean. Fennel has been used for years as a food, medicine and flavoring. I like taking a small handful of fennel seed and eating them raw when my stomach is a bit off.
Florence fennel is named after the city where it was discovered. While wild fennel is grow for its leaf and seed production, Florence fennel is a shorter plant that forms a bulbous stem at the ground level. This stem has a mild licorice flavor, great crunch and a sweet taste. I often chop it up and to make a raw salad with olive oil and balsamic vinegar. You can also roast it to bring out the sweet flavor. Florence fennel will eventually form a flat, yellow, flower head if you don’t harvest the plant. It’s good to leave some fennel flowers in the garden because they’re favorites of beneficial insects and you may get some seeds to harvest too.
Florence fennel grows best in cool, moist conditions. Sow seeds or transplants now to mature in early summer or sow in mid summer for a fall harvest. I like ‘Orion’ and ‘Solaris’ for varieties. If you don’t thin plants well or they get heat or water stressed they may not form bulbs. Even so, you can still eat the ferny foliage or cook it in soups.
