How to Grow and Care for Fennel

Foeniculum vulgare and Foeniculum vulgare var. azoricum

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.

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.”

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.

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.

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!

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.

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.”

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.

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.

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.

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.

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.

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.

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!

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!

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