Fennel Companion Plants (and Some to Avoid)

Curious about fennel companion plants and how they fit into your veggie garden? Whether you’re just starting out with growing fennel or already love adding this aromatic fennel plant to your edible garden, understanding what fennel is and how it interacts with nearby crops can make all the difference. The truth is, fennel does not always get along well with other plants. After writing nearly 50 posts about companion plants for various flowers, herbs, vegetables, fruit trees, and shrubs that grow in my USDA Garden Zone 8 small farm, I noticed that fennel was often listed as a bad companion plant. So what does fennel get along well with? Read on for ideas about pairing it with other herbs, flowers, and vegetables. I also give practical tips about how to use fennel and fresh fennel cooking tips. If you enjoy cooking with fennel, you’ll discover simple ways to grow, harvest, and make the most of this flavorful favorite.

What is Fennel

Fennel is a fragrant, edible plant known for its mild licorice-like flavor. It belongs to the carrot family and produces feathery green leaves, yellow umbrella-shaped flowers, and either a swollen bulb or tall stems, depending on the variety. The bulb, stalks, fronds, and seeds are all used in cooking, making it a versatile addition to an edible garden. I appreciate fennel’s subtle flavor in Italian sausage, and enjoy popping a seed or two in my mouth every once in a while. Let’s get started with learning which plants fennel can have as neighbors so you can grow your own. 

Fennel Companion Plants: Flowers

The list is short, but here are some reliable floral fennel companions:

Nasturtium: Acts as a trap crop for aphids, drawing them away from fennel

Cosmos: Brings in pollinators and beneficial insects that support a healthy garden ecosystem

Chamomile: Attracts hoverflies and parasitic wasps that help control harmful insects

Yarrow: Lures predatory insects and improves overall biodiversity near fennel

Echinacea: Draws pollinators and beneficial insects while adding diversity to the garden

Sweet alyssum: Attracts hoverflies and other beneficial insects that prey on pests

Fennel Companion Plants: Herbs

Fennel grows well alongside a few herbs. Here are some popular fennel herbal companions:

Cilantro: Draws hoverflies and other beneficial insects that support pest control

Chamomile: Brings in pollinators and beneficial insects that improve garden health

Chervil: Encourages beneficial insect activity and thrives in similar growing conditions

Anise: Supports pollinators and shares similar care needs with fennel

Lovage: Attracts beneficial insects and adds diversity to the herb garden

Fennel Companion Plants: Vegetables

Fennel does have difficulty growing with some vegetables, as it has been known to inhibit growth, but here are a few veggies that don’t mind having fennel in the neighborhood:

Lettuce: Grows quickly and can benefit from fennel’s light shade in warm weather

Spinach: Thrives in similar conditions and can help cover soil to retain moisture

Kale: Tolerates nearby planting and benefits from a diverse garden ecosystem

Onions: Strong scent may help deter some pests and uses different soil layers

Leeks: Similar to onions, they occupy different space and can help with pest balance

What Not to Plant With Fennel

Fennel is generally considered a poor companion (especially to many vegetables) due to its ability to suppress nearby plants. Here are some that are notorious for needing to stay away from fennel:

Tomatoes: Fennel releases compounds that can inhibit tomato growth and reduce yields

Beans: Growth can be stunted due to fennel’s allelopathic effects

Peppers: May struggle to thrive when planted too close to fennel

Eggplant: Sensitive to fennel’s root chemicals and can show poor development

Carrots: Closely related and may cross-pollinate or compete heavily for nutrients

Potatoes: Can experience reduced growth when near fennel

Coriander: Often negatively affected by fennel’s presence despite being in the same family

Quick Reference Fennel Companion Plants Chart

If you are unsure about a fennel companion plant that is not listed, you can always plant fennel in a container. For now, here’s a companion plant chart of the good and bad fennel companion plants that I know about. If you have experience with growing fennel with other plants that are not on the list, I’m always happy to edit and revise to include a wider variety of plant specimens.

Fennel Companion Plants
Fennel Companion Plants: Flowers	Fennel Companion Plants: Herbs
Chamomile	Anise
Cosmos	Chervil
Echinacea	Cilantro
Nasturtiums	Lovage
Sweet alyssum
Yarrow	Worst Fennel Companion Plants
	Beans
Fennel Companion Plants: Vegetables	Carrots
Leeks	Coriander
Lettuce	Eggplant
Kale	Peppers
Onions	Potatoes
Spinach	Tomatoes

 

Frequently Asked Questions About Fennel

Where is the best place to plant fennel?

The best place to plant fennel is in a sunny, well-drained spot with fertile soil and plenty of space away from other plants. Because fennel can inhibit the nearby growth of a variety of plants (as previously noted), it’s ideal to give it its own area or plant it along the edge of your garden or in a separate bed within your edible garden.

When is the best time to plant fennel?

The best time to plant fennel is in early spring after the last frost, or in late summer for a fall harvest. It prefers cooler temperatures for germination and early growth, so avoid planting during the peak heat of summer.

Will fennel grow back every year?

Fennel can grow back every year, but it depends on the type and your climate. Herb fennel is a perennial in mild climates and will return each year, while bulb fennel is usually grown as an annual and replanted each season. In colder areas, even perennial fennel may die back in winter but can regrow in spring if the roots survive.

Will fennel planted from seed turn into a bulb?

Not always. Whether fennel grown from seed forms a bulb depends on the variety. Florence fennel (also called bulb fennel) is specifically bred to produce a swollen, edible bulb, while common or herb fennel grows tall and feathery without forming a true bulb. Always check the seed packet to be sure you’re planting a bulb-forming type if that’s what you want.

Common Pests of Fennel

Fennel is generally easy to grow, but a few common garden pests can show up, especially in warm weather or crowded beds. Keeping fennel well-spaced, watered properly, and free of debris goes a long way in preventing most pest issues.

Aphids: These tiny sap-sucking insects cluster on stems and fronds, causing curling leaves and sticky residue. A strong spray of water or insecticidal soap usually keeps them under control.

Caterpillars (especially swallowtail butterfly larvae): These green, striped caterpillars love fennel and can quickly chew through foliage. They’re often left alone since they turn into beautiful pollinators, but you can hand-pick them if damage is heavy.

Spider mites: These microscopic pests thrive in hot, dry conditions and cause yellow speckling on leaves along with fine webbing. Increasing humidity and rinsing plants regularly helps prevent infestations.

Cutworms: These larvae live in the soil and chew through young fennel stems at the base, often killing seedlings overnight. Using collars around young plants can help protect them.

Slugs and snails: They feed on tender young growth, leaving ragged holes. Hand-picking, barriers, or organic slug bait can help manage them.

Common Diseases of Fennel

Fennel is fairly resilient, but a few common plant diseases can affect it, especially in damp or crowded growing conditions. Giving plants plenty of space and watering carefully makes a big difference in keeping them healthy.

Powdery mildew: This fungal disease shows up as a white, dusty coating on leaves and stems, often in warm, dry weather with poor airflow. Prevent it by spacing plants well and watering at the base; treat with neem oil or a baking soda spray if needed.

Downy mildew: Unlike powdery mildew, this appears as yellow patches on the tops of leaves with grayish fuzz underneath, usually in cool, humid conditions. Good air circulation and avoiding overhead watering help reduce risk.

Root rot: Caused by overly wet soil and poor drainage, root rot leads to wilting, yellowing, and eventual plant collapse. Plant fennel in well-draining soil and avoid overwatering to prevent this issue.

Leaf blight: This causes brown or black spots on foliage that can spread and kill leaves. Removing affected leaves and keeping the garden clean helps limit spread.

Damping-off: A common problem for seedlings, this disease causes young fennel plants to suddenly collapse at the soil line. Using clean soil, proper spacing, and good drainage helps prevent it.

How to Harvest Fennel

Harvest fennel based on the type you’re growing. For bulb fennel, cut the bulb at soil level when it’s about tennis ball size, before it becomes tough or starts to split. You can trim off the stalks and fronds, leaving a small portion of the base in the ground, and it may produce smaller side shoots.

For herb fennel, snip the feathery fronds as needed once the plant is established, taking no more than a third at a time to keep it healthy. If you want seeds, allow the plant to flower and dry, then cut the seed heads and let them finish drying before collecting.

Uses for Fennel and Cooking Tips

Fennel is incredibly versatile in the kitchen. The bulb can be thinly sliced and added to salads, roasted, or sautéed for a sweet, mild flavor. The feathery fronds make a fresh garnish or can be chopped into sauces and dressings. Fennel seeds add a warm, licorice-like note to baked goods, spice blends, and teas. You can also braise the stalks or include them in soups and stews for subtle depth.

Need More Planting Ideas?

Check out the tips for the best companion plants for eggplant to learn what to grow with those beauties. If you like the idea of companion planting, you might be interested in reading about the best companion plants for pumpkins, sunflowers, garlic, asparagus, rosemary, radishes, beetroot (beets), thyme, lupine, borage, stevia, or the best companion plants for lavender. Get tips for growing stunning dahlias. Are you a beginning gardener? Try planting some foolproof, easy-care perennials, or learning about the best companion plants for columbine. There are so many exciting plants to grow!

Keep Track of Your Garden with a Journal Logbook

Now that you have learned about some compatible companion plants, keep track of your planting ideas, goals, and plans with a printable, editable free garden journal logbook. Choose the pages you want to use and customize them as you wish to record monthly, weekly, and daily garden tasks, lists, weather, and planting arrangements. There are also grid pages for easily designing the layout of your vegetable garden, flower garden, or landscape. Print it out and put it into a notebook you can take with you to the garden (that’s what I do). It’s nice to have all of your garden information in one place.

Get the garden journal logbook!

Free Online Garden Planner Layout Template

Now that you know which are the best companion plants for parsley, you might need a way to plan your garden layout. Whether you are planting vegetables, flowers, or herbs near your parsley plants, this online garden planner can help you visualize your design and bring it to life. Arrange and rearrange the plants over and over, then print the layout when you are satisfied. With garden tasks that need your attention, this is one way to save time.

It’s fully customizable when you make your own copy and includes two editable chart pages for noting planting specifications.

Get my free online garden layout planner template!

Have a wonderful week, and may all of your fennel-growing endeavors meet with success!

Lisa Mitchell is a wife, mom, and school librarian who likes to grow fruit, herbs, vegetables, and flowers on her family’s small Pacific Northwest farm. To learn more about what this website has to offer gardeners, click on over to the Garden page.

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