Fennel is a conversation starter both at the market and in my neighborhood.
Almost without fail, every time I used to buy fennel at the store, the cashier would ask me “how do you cook with this?”
Now that I grow fennel and have a magnificent perennial stand of it that stands tall in a corner of my garden, each year neighbors inevitably ask me what the heck that plant is. Usually, they guess that it’s dill and are surprised to learn that it is, in fact, fennel in its fullest form.
A couple of years ago, I discovered that fennel fronds, when cut and left on top of soil, will attract slugs in massive quantities for easy disposal.
Fennel isn’t just a focal point or garden pest helper, though - its range of versatility in the kitchen is where it really shines. Shave the bulb raw, use it in stir-fries like you would onion or in soups like you would celery, save the stems for making homemade broth, dry the fronds and seeds for seasoning and teas. Even the pollen is prized by fancy chefs, who you can emulate at your next gathering to impress your friends.
This guide covers everything you need to know to grow fennel regeneratively in your organic garden. From soil preparation to harvest, you’ll learn how to enhance your ecosystem and your cooking with this phenomenal…or fennomenal? plant.
Let’s start with a little bit about how fennel is an asset in the sustainable garden.
Real quick: I have several articles that go over regenerative gardening in detail, but for the sake of this article, let’s summarize.
The mission of regenerative gardening is to transform our backyards into resilient landscapes that sequester carbon, enrich soil health, and create thriving habitats. Oh yeah, and to grow abundant amounts of healthy food, too.
It’s important to honor that many Indigenous, Asian, MENA, and African societies have been practicing regenerative farming techniques for millennia.
The basic principles of regenerative gardening are:
All of this adds up to carbon-rich and fertile soil that grows amazing food while tending to the planet at the same time.
Fennel plays several important roles in a regenerative garden ecosystem:
Attracts Beneficial Insects: Each year, I look forward to hearing the loud hum of bees and even friendly wasps as they work through the pollen of my blooming fennel. This plant also creates a habitat for butterflies like the Swallowtail, and I have fennel to thank for the number of these beauties that grace my garden. Other beneficial insects like ladybugs are also attracted to this plant, which come in to help with natural pest control.
Studies show just how wide a range of insects spend time around fennel:
Many of these insects offer great organic pest control features as a part of their ecosystem services, or are pollinators to boost crop production. As an added benefit, Colley & Luna in their 2000 research paper notes that since fennel flowers towards the end of the season, they help extend the population of beneficial insects into the fall when not many other plants are blooming. With bloom lengths as long as 7 weeks, they’re a great asset to the regenerative garden.
All together, this promotes biodiversity and a balanced ecosystem.
Companion Planting: Fennel is a great a companion plant to naturally deter pests from other crops.
As a gardener in the PNW, most of my year is spent figuring out how to remove slugs from the garden. I inadvertently found out that fennel frond clippings, spread around the garden, will collect slugs in massive numbers for easy removal. It works best after a day of rain.
→ Note that fennel is considered to be allelopathic, which means it sends out growth inhibiting chemicals in the soil that can negatively impact other plants. Fennel extract has been scientifically studied for its use in preventing weed germination, so this could be utilized to your advantage in certain situations.
However, another study showed that extracts of fennel stalks and leaves reduced germination and root development of food crops like rye, radish, and lettuce. This allelopathy is one reason why fennel can become invasive.
When planting fennel next to other plants for bulb production, observe what happens in your garden and adjust accordingly. I’ve successfully grown fennel with plenty of plants from brassicas to calendula, beets and beans. So it may not always be a negative factor.
Soil Health: University of Wisconsin Madison mentions that, as a member of the carrot family, fennel has a deep taproot. If your soil isn’t very compacted, fennel’s taproot can get quite long. At harvest, cut the fennel bulb at the base so that the tap root remains in the soil and can break down as microbes feed on it. In turn, this will build up organic matter and build soil health.
Nutrient Accumulation: Since its roots also help draw nutrients from deep in the soil profile, fennel is known to accumulate minerals which can then become available to other plants. A project funded by Sustainable Agriculture Research and Education found fennel to be considered a “dynamic accumulator” of magnesium and manganese.
The database also notes that fennel can provide a good amount of phosphorus and potassium, even though it’s not in the “dynamic” category for those nutrients.
Stacking Functions: While the idea of “stacking functions” is a permaculture principle, it certainly has its place in regenerative gardening too. Fennel in an of itself offers many functions: the bulb is a tasty vegetable, the stalks can be used for chop-and-drop applications, the fronds, pollen, and seeds offer seasoning. All the while, it provides ornamental function and attracts friendly insects into your backyard.
Perennial Crop: As a hardy perennial in many climates, fennel can provide a consistent source of herbs, and habitat for beneficial insects year after year without the need for annual replanting.
Regenerative farming favors perennial plants. As Project Drawdown mentions, this is because they can also sequester more carbon and enhance the soil health more than standard annuals.
Bulbing Fennels: Known for developing sizable “bulbs” at the base of the plant, bulbing fennels usually won’t produce flowers and seeds until their second year. Harvest the bulb in the first year as it will become very tough once the plant goes to seed. Usually ready in 70-80 days.
Herb Fennels: Grown for ornamental and herbal value, these plants are harvested for their fronds and seeds. These varieties can produce seeds in their first year, but don’t worry if they don’t - they’ll produce in year two.
Early Spring Sowing:
Sow fennel seeds a week or two before your last frost for a summer solstice harvest. For spring sowings, direct sowing in the garden is best if you get a steady dose of rain during this time.
However, you may wish to read on to find out why you should sow fennel after summer solstice!
Sowing in July for a Fall Harvest:
You’ll get your best harvest of bulbing varieties if you do a second sowing right at solstice - according to Osborne Quality Seeds, most bulbing fennel actually prefers when the days get shorter as it grows.
This mirrors my experience - after chasing the size of the dense fennel bulbs that you can find in the grocery store, I realized that planting them in the spring was only giving me so-so results.
For mid-late summer planting, I like to sow fennel in modules indoors so that I can keep the soil moist during our summer droughts. Fennel seeds have a high germination rate in my experience, so I only sow one seed per cell. I plant the seed 1/2 inch deep.
Germination:
Germination can take 1-2 weeks, so keep your soil moist during this time until all plants have sprouted.
Seedling Care:
Fennel is a heavy feeder plant that enjoys nitrogen. While I usually don’t fertilize my seedlings until I transplant them out into my garden, fennel may be a plant that would do well with a diluted organic liquid fertilizer that can provide an extra source of nitrogen as it grows. I wait until seedlings are 4 inches tall to provide them with this boost.
Transplanting:
Transplant fennel out into the garden when plants are around 6 inches tall. Water them in well.
Spacing requirements:
In the garden, Utah State Extension recommends planting fennel with a spacing of 8-12 inches. Keep the area well-weeded, as weeds will hinder bulb development.
Watering and Mulching:
If you’re sowing bulbing fennel for a fall crop, mulch around plants with weed-free grass clippings. This will keep the soil cool, help retain moisture, and provide a bit of nitrogen to the fennel as it breaks down over the season. Summer-sown fennel is a good candidate for drip irrigation and continual mulching, as it will perform better with steadily moist soil.
Herb fennel varieties are more drought tolerant, especially in their second year and beyond. My stand of perennialized fennel hardly needs supplemental water, even during hot dry summers. Mulching around herb fennel is still a good idea for added soil health, though.
Fertilization: A key change that I made to my fennel growing set up that helped in addition to a post-solstice sowing was a focus on nitrogen fertilizer for my plants. Go for organic options, and help the fennel out with some homemade compost teas made from nitrogen-rich nettles, aged chicken manure, and mulch made from grass clippings.
You can also make your own nitrogen amendment with nettle compost tea. Mulch with around 1 inch of grass clippings regularly throughout the season.
Beneficial companions
Beans of any kind are a great candidate for planting with fennel.
One strategy can be to plant fennel in early spring, with fall-sown fava beans, just as the plants are coming into bloom. The fava beans will be ready to harvest before the fennel reaches its full size, and you can cut back the fava bean plants for a great mulch. The nitrogen fixing nodules on the fava bean roots will break down and become available to the hungry bulbing fennel.
I’ve also had success with pairing bush beans with fennel, where the fennel provided some much needed shade from the summer heat to protect the bean plants from scorching.
A similar garden plan would be to plant fennel in late July/early August within a stand of May-sown peas. The peas will be complete with their harvest as the fennel is getting established, and can be cut back. The nitrogen nodules of the pea roots can support the growing fennel.
In contrast, a perennialized herbal fennel can serve as growing supports for peas in the spring.
I like to plant lettuces behind my perennialized stand of herbal fennel, facing east. The fennel blocks the harsh heat of the sun as it moves west during the day to provide much-needed shade for this crop in the summer months.
As mentioned above, fennel can be allelopathic, meaning it might inhibit growth of nearby plants. Observe what happens in your own garden to see what works best.
Pest Deterrents and Beneficial Attractants
In some gardens, aphids can be a pest for fennel. Luckilly, fennel naturally attracts a slew of beneficial insects who feed on aphids.
However, any other plant that make your garden a habitat for aphid predator insects can provide an extra boost. A study by Kaushalya Amarasekare, published by Tennessee State University’s Cooperative Extension lists the following plants to attract aphid-hungry insects:
Harvesting fennel at the right time ensures you get the best flavor and texture. Here’s a step-by-step guide:
Fennel Bulbs:
Fennel Fronds:
Fennel Seeds:
Bulbs:
Fronds:
Seeds:
Fennel is in the Apiaceae, or Carrot, family. If you are foraging and think that you’ve come across a stand of wild fennel, it’s very important to know that many plants in the carrot family are highly toxic. Here’s an article from a University of California Master Gardener on the similarities and differences of the two. Consult an expert local forager before eating anything wild grown that looks like fennel/queen anne’s lace/carrot.
Since some of these toxic plants can make their way into your garden, it’s always good to know if you’re looking to determine whether you have a self-sown fennel plant or a bird-planted poison hemlock plant. When planting dill, carrots, nigella, black cumin, fennel, or parsnip in your garden, be sure to label them clearly so that you know what you’ve planted there! When in doubt, throw it out and wear gloves when removing.
Dill (Antheum graveolens): Edible. It’s quite common to mistake herb fennel or a perennialized bulbing fennel for dill. It’s tall, has fronds for leaves, and clusters of small yellow flowers.
The easy ways to distinguish the two are through scent and seeds. Fennel is strongly anise-licorice scented, and dill is more earthy-spicy. Fennel seeds are more oblong, while dill seeds are more ovate. NC State Extension also advises that dill has hollow stems whereas fennel does not.
Dill’s leaves are a bit thicker and more compact, while fennels are longer and more wispy.
Nigella/Cumin/Love-in-a-Mist: Ornamental. The fronds of this plant look similar to fennel, but as soon as the buds start to form it becomes clear that its’ a flower. Nigella is sometimes called Fennel Flower to add to the confusion!
For me, fennel is an essential staple in my regenerative garden. From the vibrant hum of bees and butterflies to the unexpected discovery of fennel’s slug-attracting fronds, this plant continues to surprise and delight. I love adding the bulbs to stir-fries and as a celery replacement in sofrittos, and often add the seeds into dishes for added flavor.
I hope this guide has inspired you to give fennel a place in your own regenerative garden. Remember, every step you take toward sustainable gardening practices makes a difference, not just in your backyard, but for the planet as a whole.
1. When is the best time to plant fennel?
2. How do I prevent fennel from becoming invasive?
3. Can fennel grow in containers?
4. What are some common pests that affect fennel?
5. How can I use fennel fronds in cooking?
6. What the heck do you do with the bulb?
