Growing and Harvesting Fennel

Foeniculum vulgare and Foeniculum vulgare var. azoricum

A closeup of a stalk of bulb-type fennel growing in a garden setting.

There are two types of sweet fennel. The first is the common or herb type, Foeniculum vulgare, prized for the anise-like flavor of its feathery leaves and robust seeds.

Common Sweet Fennel (Foeniculum vulgare) growing in a backyard herb patch.

The second is Florence or bulb style, which produces crisp celery-like bulbs bursting with anise-like flavor in addition to fragrant foliage and seeds. In my family, this vegetable has always been a holiday treat known by its Italian name, “finocchio.”

Florence or bulb style fennel, aka finocchio, sliced on a cutting board.

Would you like to grow them your veggie garden? Read on to for the details!

The Fundamentals of Fennel

Fennel is grown from the edible seeds that are produced after the flower blossoms fade. Here’s how to get started on your crop.

Sowing Seeds

This is a cool weather crop that matures best without enduring summer’s intense heat. Sow in early spring or late summer for best results.

Fennel seedling planted in garden soil.

In zones 6 to 10, you may grow it as a perennial or possibly biennial. However, it won’t withstand hard frost and grows in most places as an annual. In California, it has become invasive, so check its status in your region before you plant.

To cultivate varieties of F. vulgare, choose a location with full sun that is close to a water source. The soil should be organically rich and on the acidic side, so amend it with compost if necessary. You may want to do a soil test to evaluate your earth.

Sow seeds directly into the ground a few weeks before the last predicted frost date, or start them indoors about six weeks ahead of the growing season. Get a jump on germination by soaking them overnight so they sprout before placing them on top of damp soil. Tamp lightly to cover the seeds with dirt and maintain even, but not overly-saturated moisture.

Rows of fennel seedlings in planter trays.

You may try growing fennel in containers on a patio or balcony. Two things to remember here:

  1. The tap root is about a foot long, so you’ll need a deep pot.
  2. Pots dry out quickly, so be vigilant with watering.

Some folks believe that fennel and dill cross pollinate if planted in proximity to one another. Others pooh-pooh that theory. Keep this in mind, and see what happens in your garden!

Human arms plant a line of fennel seedlings in an herb garden.

As the first true leaves begin to appear, thin seedlings to about a foot apart from each other. Transfer seeds started indoors to the garden at this time. Let them acclimate to the outdoors by remaining in their seed starter pot for a day or two to harden off before transplanting into the garden at one-foot intervals.

Ideally, bulbs mature before flower buds appear. You won’t get blossoms or seeds if you harvest the bulbs, but the vegetable will be at the peak of sweetness. Starting seeds indoors is one way to hasten the process.

Nurturing Your Crop

Bulb-less plants in green and bronze varieties may reach five feet in height, forming a texturally-rich backdrop of feathery leaves in borders and beds. Keep the soil evenly moist as flower heads of tiny yellow blossoms appear, followed by fragrant seeds.

A mature fern-like fennel plant growing in an herb garden.

Bulb varieties may reach three feet tall as fine, dense leaves form and the vegetable begins to enlarge. Once you see swelling, mound dirt up around the bulb to protect it from sunburn. This technique is called “blanching.”

Florence type fennel bulbs covered with compost.
Adding mulch over the top of the bulb-like roots of the Florence varieties ensure that they remain white and more satisfying in culinary endeavors.

Continue to water regularly but avoid over-saturation and the ponding of water to prevent rotting. You may fertilize lightly during this time.

To get the best bang for your buck, snip the ends of the foliage before they begin to bud for exceptional bulb development. Preventing the formation of buds – and hence, seeds – is also an excellent way to curb the invasive tendencies of the plant.

A mature fennel plant with small yellow flowers going to seed in an herb garden.

In areas where summer heats up quickly, you may be better off planting mid- to late-summer for a fall crop. If you should have a particularly warm spell, plants may “bolt” or suddenly go to seed, and maturity comes to a grinding halt. Foliage and blossoms may be usable, but immature bulbs may be a loss.

Harvesting

Delicate and delicious foliage and blossoms may be harvested throughout the growing season for use in salads, and as attractive garnishes. You may even pick the tender young shoots of seedlings to eat as tasty microgreens.

A mature Florence style finocchio fennel plant growing in a backyard vegetable garden.

The rule of thumb here is to harvest bulbs when they are about tennis ball-sized. Slice each off cleanly at ground level with a clean knife, and slice the elongated stems and profusion of leaves off at about three to six inches above the bulb. All parts are edible.

A trimmed and cleaned finocchio bulb laying on a rustic wooden table.

I like to slice the bulbs thickly and store them in an airtight container with a little water in the fridge. Each morning I change the water and they last for three days. After that, they start to turn brown on the edges.

Alternatively, you may place whole vegetables in an airtight plastic bag in the refrigerator for about a week. Foliage tops and stems may also be stored in an airtight plastic bag in the fridge for up to a week. Wash before serving.

Read more about storing and using fresh fennel at our sister site, Foodal.com.

Dry seeds should remain robust and aromatic for several years when stored in an airtight jar.

Foodal also has some great ideas for using the seed for flavoring in your cooking.

Diseases and Insect

You should have few issues with F. vulgare in its various forms. Aphids or white flies may occasionally be a nuisance, but provided you don’t over- or under-water, all should be well. One visitor you may have is the parsley worm.

A closeup photo of a swallowtail caterpillar crawling on a fennel plant

This little guy is the caterpillar stage of the black swallowtail butterfly. You may pick him off, or decide to share some foliage, as it is a beneficial garden pollinator.

Where to Buy

Florence variety seeds are available from Burpee.

Burpee Fennel, Florence

Florence Bulb-Style Fennel via Burpee

Orion hybrids are also available from Burpee. You may buy a 100-seed packet or a set of three plants. This compact type is less susceptible to tip burn than others, and it matures in 80 to 85 days.

Fennel, Orion Hybrid

Orion Hybrid Fennel via Burpee

Bulb-less Bronze-type seeds are available from True Leaf Market.

Bronze Fennel leaves made into a bouquet. White, isolated background.

Bonze Leafy Fennel via True Leaf Market

Even without the vegetables, the leaves are beautiful in the garden and delicious on the table. Blossoms produce seeds that may be dried for culinary use.

Recipe Ideas

Organic Brussels Sprouts Sautéed with Bacon, Fennel Seed, and Dill

If you’ve never like Brussels, then you haven’t tried them al dente, cooked with bacon, and flavored with the taste of fennel and fresh dill.

Top-down view of Organic Brussels Sprouts Sauteed with Bacon, Fennel Seed, and Dill in a white ceramic bowl on a dark maple butcher board surface.

Besides the incredible flavor, the fat from the bacon allows fat-soluble nutrients to absorb more easily into the body.

Get the recipe now on Foodal.

Balsamic Tomato & Fresh Fennel Sauce for Bruschetta

Are you looking for an easy, no-cook sauce to make a quick crostini or bruschetta? Try this tasty recipe, prepared with fresh fennel and cherry tomatoes.

Closeup of Balsamic Tomato and Fresh Fennel Sauce for Bruschetta on toasted wheat bread.

You can also serve this tasty sauce on top of pasta, spiralized veggies, or anything you would usually serve with marinara.

Find the recipe now on Foodal.

Fennel Nettle Iced Tea

Do you love a good healthy tea?

Oblique view of a white mug full of Fennel Nettle Iced Tea.

This fennel nettle iced tea blend is naturally sweet and has powerful natural benefits. It’s a tasty take on a ubiquitous beverage, with unique flavors.

Find the recipe now on Foodal.

Flavor and Versatility

Now you have to low-down on sweet fennel varieties. If you love the crunch of celery, and the licorice-like flavor of anise, this healthy herb/vegetable is going to be the star of your garden and your table this season.

Closeup of the seed top of a mature fennel plant.

Some folks like to dry the seeds to use as seasoning. Others chew or brew them as a digestive aid. And the pollen – oh, the pollen! It imparts a concentration of flavor you just won’t believe.

Try growing fennel in your herb garden this spring!

And if you’re a fan of growing herbs, you’ll love some of our other growing guides:

© Ask the Experts, LLC. ALL RIGHTS RESERVED. See our TOS for more details. Product photos via Burpee and True Leaf Market. Uncredited photos: Shutterstock.

Related Posts
Filter by
Post Page
Perennials Fruit Vegetables Orchards, Nuts, and Fruit Trees Landscape Trees Flowers Herbs Annuals
Sort by

About Nan Schiller

Nan Schiller is a writer with deep roots in the soil of southeastern Pennsylvania. Her background includes landscape and floral design, a BS in business from Villanova University, and a Certificate of Merit in floral design from Longwood Gardens. An advocate of organic gardening with native plants, she’s always got dirt under her nails and freckles on her nose. With wit and hopefully some wisdom, she shares what she’s learned and is always ready to dig into a new project!

Leave a Comment