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Planting and Growing Fennel Bulbs and Fronds

Fennel Bulb growing in the garden
Image Credit:
Nnattalli
Botanical Name
Foeniculum vulgare var. azoricum
Life Cycle
Perennial
USDA Zones
5a
5b
6a
6b
7a
7b
8a
8b
9a
9b
10a
10b
Toxicity
Non-toxic
Sun Exposure
Full Sun
Water Needs
Moderate
Height
1–3 feet
Spread
1–3 feet
Soil pH
Neutral
Bloom Time
Summer
Flower Color
White
Yellow
Special Features
Container-Friendly
Fragrant
Attracts Butterflies
Attracts Pollinators
Deer-resistant
Resilience
Drought-Tolerant
Heat-Tolerant
Plant Type
Vegetables
Written By: Andy Wilcox Master Gardener and Gardening Contributor
Almanac Guide to Herbs

Want a garden superstar that tastes amazing and brings all the pollinators to the yard? Meet fennel! This vibrant, feathery beauty is not just a feast for your eyes but also a flavor powerhouse—from crunchy bulbs to aromatic seeds and fresh fronds. This easy-to-love herb is a win-win for your kitchen and your garden’s buzzing visitors. Ready to plant some fennel magic?

Fennel is grown as a tasty vegetable, as an ornamental for its beautiful and delicate foliage, as a pollinator attractor, and for its pungent and flavorful seeds. It’s one of our favorite edible flowers to grow! Easy to grow by direct seeding in midsummer, fennel deserves a spot in your herb garden or flower bed.

Florence fennel is the common name for Foeniculum vulgare var. azoricum, the biennial bulbing fennel grown as an annual for eating. While it can grow quite tall, shorter varieties are available, perfect for smaller spaces. 

Also called finocchio, this tasty vegetable is eaten fresh, baked, and roasted. It’s used as an ingredient in soups, and its fresh leaves are used to flavor teas. The seeds are likely familiar to you as an essential flavoring in Italian sausage, as well as pastries and candies. It’s also one of the ingredients in the famous Chinese five-spice powder.

While not a native, fennel is a lovely and functional plant for pollinators, and the plant is a host for anise swallowtail and black swallowtail caterpillars! It can spread in warmer climates but rarely does so in cold areas.

fennel flower
Many pollinators love the beautiful fennel flowers!

Planting

When To Plant Fennel

Fennel can be planted in spring, as soon as the frost danger has passed, but is better grown as a fall crop. It is prone to bolting if it matures during hot weather and long days. Instead, plant fennel in midsummer for a fall crop. 

Since fennel does best as a cool-weather crop, it’s perfect to plant in your garden when earlier-maturing crops are finished. Time it to be ready just before your first frost, as the foliage and bulb are only lightly frost-tolerant. Direct seed about 80 days before your first frost date, depending on the variety.

Where to Plant Fennel

Florence fennel likes full sun and fertile, well-draining soil. Work some organic matter in, but don’t overdo it. Soil that is too rich will result in bland, flavorless bulbs and foliage. A neutral pH of 6.5-7.5 is ideal for these heavy feeders.  

Common fennel can grow as high as 6 feet tall. If growing as an ornamental, place it in the back of a bed where its delicate foliage can be seen but won’t block the view of other, shorter plants.

How To Plant Fennel

Fennel can be directly seeded or transplanted, although transplanting can be tricky due to the tap root. Soaking fennel seeds for 24 hours can aid in germination.

To start fennel indoors:

  • About 4–6 weeks before your last frost, sow 2–3 seeds per cell in standard trays or soil blocks. 
     
  • Sow seeds ¼ inch deep. 
     
  • After germination, thin to one seedling per cell by snipping, not pulling.
     
  • Harden off seedlings before transplanting into the garden.
     
  • Fennel can be transplanted outdoors as soon as frost danger has passed. Don’t start them too early—fennel forms a taproot and can suffer extreme transplant shock if the taproot is injured.

Direct seeding after the last frost in spring or in midsummer:

  • Prepare the bed with compost, working it into the soil. 
     
  • Sow seeds ¼ inch deep, about one inch apart, in rows 18 inches apart.
     
  • Gently water the seeded area. 
     
  • Once plants have a set of true leaves, thin to a spacing of 6–9 inches apart. 

Growing

  • Fennel likes fertile soil that is high in organic matter.
  • Mulch to keep soil moisture even and slightly moist. 
  • Fennel typically blooms in the second year but can bolt in the first year (ruining the crop) if exposed to high heat and long days. If your transition from spring to summer is early and rapid, consider a late summer into fall crop for better success.

Watering Fennel

Fennel likes an inch of water per week or more but is drought tolerant once established (thanks to that taproot). 

Tip: Water in the morning. The plants will have water available during the heat of the day when needed most, and foliage will have a chance to dry before nightfall. Constantly damp vegetation can cause fungal issues. If your mornings are busy, consider a timer to turn your irrigation on and off.  

Harvesting

Fennel is grown as an annual for foliage and as a vegetable. You can clip the fronds to use once the plant is established; they make a tasty addition to salads, teas, and more. Its tasty bulb can be harvested early as “baby” fennel, at about 3 inches in diameter, or allowed to mature to a 4–5 inch size fully. Many people prefer to harvest their fennel when the bulb is the size of a tennis ball for the best flavor and texture. 

Mature fennel bulbs are delicious on the grill!

How to Pick Fennel

  • Harvest using a garden knife or pruning shears, cutting at the base of the plant above the tap root. 
  • Store fennel in a cold environment with high humidity. If storing, cut the stalks and vegetation off about an inch above the bulb.
  • Fennel seeds from second-year plants can be harvested when the flower head has turned brown. Snip off the heads and lay them on a screen or tray to dry. The heads will shatter, releasing the seeds.
fennel harvested in a wooden bowl

Pests and Problems

  • Root rot in wet soils.

Types

  • ‘Orazio’ is a hybrid with heavy, round, white bulbs and a crisp, anise flavor. 
  • ‘Fino’ is an open-pollinated variety with a good bulb and is bolt-resistant. It’s a good choice if you are trying a spring crop. 
  • ‘Cantion’ is another slow-bolting variety suitable for early spring planting.
  • ‘Orion’ is a shorter hybrid variety that tops out at about 2 feet tall—perfect for smaller gardens. It’s also a good keeper in storage.

Wit and Wisdom

  • Fennel has been enjoyed as a culinary treat and has been used for medicinal purposes since ancient Greek and Roman times.
  • It was once thought that fennel could ward off witches! Read more herbal folklore.
  • In the language of flowers, fennel means flattery.
  • Fennel can cross-pollinate with dill, causing unwanted flavors in both, so plant them far away from each other. 

“The fennel is beyond every other vegetable, delicious. It greatly resembles in appearance the largest size celery, perfectly white, and there is no vegetable equals it is flavour. It is eaten at dessert, crude, and with, or without dry salt, indeed I preferred it to every other vegetable, or to any fruit.” –Thomas Jefferson

Vegetables
About The Author
Andy Wilcox

Andy Wilcox

Master Gardener and Gardening Contributor

Andy Wilcox is a freelance writer, flower farmer, and master gardener with over 25 years of experience in gardening, horticulture, and forestry. He is the co-owner of Stone’s Throw Flowers, a business...
Read More from Andy Wilcox

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Comments

<span>Samantha</span> Fri, 06/19/2026 - 13:42
I let my fennel go wild as it holds the soil on an embankment that's on one side of my yard. We use the seeds in lamb dishes, but otherwise do not care for it as an edible. We love the foliage and blosoms in flower arrangements however, and the house smells wonderful when we bring in each fresh batch.
<span>V Acker</span> Fri, 06/19/2026 - 09:57
Fennel is harmful to some other garden plants. Before planting, research which welcome fennel as a companion and which do not (tomatoes, cucumbers, peppers, beans, and more).
<span>Anne</span> Fri, 08/23/2024 - 09:51
Fennell is very important to certain species of Butterflies~
<span>Winie</span> Thu, 05/15/2025 - 19:19
Yes, 2 kinds of swallowtails. So if caterpillars are destroying your fennel (or your parsley and dill), let them! The plant will recover later after the caterpillars get their fill and move on.
<span>Anne</span> Fri, 08/23/2024 - 09:50
Some of Johnny Appleseed's planted Apple trees are alive today with their descendants; (northeast)~: )
<span>Robin</span> Wed, 03/27/2024 - 13:55
You forgot to mention that fennel is invasive and will take over an area. Probably something for people to know. I was going to just toss the seeds before I learned of its invasiveness. Another historical tidbit I just learned from a book, Perilous Journey by C.M. Sublette, is that Johnny Appleseed, aside from planting apple seeds where ever he went, also tossed fennel seeds and was responsible for them growing wildly across country wherever he had been.