Green and Bronze Fennel: A Complete UK Growing and Cooking Guide

Few herbs are as visually striking as fennel. Those fine, feathery fronds - either fresh green or a deep, burnished bronze - bring genuine elegance to the garden, while the flavour they deliver to food is one of the most versatile in the culinary herb repertoire. Sweet, anise-scented, and slightly warming, fennel works in everything from grilled fish to slow-cooked pork to simple summer salads.

In this guide we'll cover how to grow both green and bronze fennel in the UK, how to harvest it, and how to make the most of it in your cooking. Ready to grow? You'll find fennel plants at the Culinary Herb Co.

Green Fennel vs Bronze Fennel: What's the Difference?

Both are the same species - Foeniculum vulgare - and both are grown in exactly the same way. The key differences are cosmetic and, to a small degree, practical:

• Green fennel (Foeniculum vulgare): the classic, fresh green form. Vigorous and productive, with bright fronds and a clean anise scent.

• Bronze fennel (Foeniculum vulgare 'Purpureum'): a striking cultivar with deep copper-bronze feathery foliage that catches the light beautifully. Slightly hardier than green fennel and considered by many to be more ornamentally impressive.

Flavour-wise, bronze and green fennel are effectively identical - the same sweet anise character, the same culinary uses. Choose green for maximum yield, bronze for visual drama. Or, better still, grow both.

Important note: both are the herb fennel, grown for their fronds, stems, flowers, and seeds. This is different from Florence fennel (Foeniculum vulgare var. azoricum), which is the vegetable grown for its bulbous base. We're focusing on the herb form here.

Where and How to Plant Fennel

Fennel is a sun-lover. Choose a spot with:

•       Full sun: at least 6 to 8 hours of direct sunlight daily. Fennel can tolerate some light shade but will be less vigorous and flavourful.

•       Free-draining soil: it dislikes waterlogged or heavy clay conditions. If your soil is heavy, dig in some grit or plant in a raised bed.

•       Shelter: young plants in particular benefit from some protection from cold winds.

 

One critical point about positioning: fennel is allelopathic, meaning it releases chemicals from its roots that inhibit the growth of many neighbouring plants. Keep it well away from most vegetables - particularly tomatoes, peppers, beans, and brassicas. It's better planted at the edge of the kitchen garden, in a dedicated herb bed, or in a large container where its root influence is contained.

Fennel does get along with dill, though even here care is needed: the two will readily cross-pollinate if grown in close proximity, which can affect flavour.

Caring for Your Fennel Plants

Once established, fennel is largely self-sufficient. Here's what it needs through the growing season:

•       Watering: keep the soil consistently moist, especially during dry spells and in the first season after planting. Once established, fennel has reasonable drought tolerance.

•       Feeding: fennel doesn't demand rich soil, but an annual mulch of compost in spring will support healthy growth.

•       Cutting back: fennel is perennial and will die back in winter before returning in spring. Cut old stems down to the base in late autumn or early spring before new growth begins.

•       Deadheading or seed collecting: if you want to prevent self-seeding (fennel can spread enthusiastically), deadhead the flower umbels before they set seed. Alternatively, let some go to seed and collect them for cooking - fennel seeds are a valuable spice in their own right.

Harvesting Fennel

You can harvest fronds throughout the growing season, from spring through to late summer. Snip young, fresh growth from the outer parts of the plant, leaving the centre to continue growing.

For seeds, wait until the flower heads (umbels) have dried and the seeds are beginning to turn from green to golden-brown. Cut the whole flower head and hang it upside down in a paper bag to catch the seeds as they fall. Dry thoroughly before storing in a sealed jar.

Fennel flowers - the small yellow blooms of the umbels - are also edible and make a beautiful garnish for salads and fish dishes.

Cooking with Fennel Fronds and Seeds

Fennel's anise flavour is sweeter and gentler than actual aniseed, with a freshness that works across a remarkable range of dishes.

Using the fronds:

•       Fish and seafood: this is the classic pairing. Scatter chopped fronds over grilled salmon, bake fish on a bed of fennel, or toss with prawns and a citrus dressing. The sweetness balances fish beautifully.

•       Salads: fennel fronds bring brightness to green salads, grain salads, and slaws. Combine with orange segments, chicory, and walnuts for a Scandinavian-inspired winter salad.

•       Sauces and dressings: blend fresh fronds into a herb sauce or vinaigrette - they work particularly well with lemon, creme fraiche, and capers.

•       Pasta and risotto: stir chopped fronds through a pasta with smoked salmon or a risotto with peas and lemon.

•       Herb butters: mix into softened butter with lemon zest and a little garlic, then chill and use to finish grilled fish or chicken.

 

Using the seeds:

•       Sausages and pork: fennel seed is the defining spice of Italian sausage. Rub whole or lightly crushed seeds into pork belly before roasting.

•       Bread and baking: add whole seeds to focaccia, crackers, or seeded loaves for fragrant depth.

•       Spice blends: fennel seeds are a component of garam masala and five spice, and work in Indian-style curries and dals.

•       Tea: steep a teaspoon of crushed seeds in boiling water for a gentle digestive tea.

Bronze fennel fronds can be used wherever green fronds are called for. The colour fades during cooking, but the flavour is identical.

Shop Fennel at the Culinary Herb Co

Browse our range of green and bronze fennel plants - all grown with care and ready to thrive in your garden.

Shop fennel at the Culinary Herb Co

Frequently Asked Questions About Fennel

What is the difference between herb fennel and Florence fennel?

Herb fennel (Foeniculum vulgare) is grown for its feathery fronds, stems, flowers, and seeds. Florence fennel (Foeniculum vulgare var. azoricum) is a different variety grown as a vegetable, harvested for its swollen, bulbous white base. The flavour of both is similar - sweet and anise-like - but they're grown and used very differently. This article covers herb fennel.

Does bronze fennel taste different to green fennel?

No - the flavour of bronze and green fennel is essentially identical. Both have the same sweet, anise character and can be used interchangeably in cooking. The difference is purely visual: bronze fennel has striking copper-tinted foliage that many gardeners find more ornamentally appealing. Flavour-wise, you won't notice any difference in the kitchen.

Why should I keep fennel away from other vegetables?

Fennel is allelopathic, which means it releases compounds from its roots that inhibit the growth of many neighbouring plants. Tomatoes, beans, brassicas, and peppers are particularly affected. For this reason, fennel is best positioned away from the main vegetable patch - at the edge of a herb bed, in its own dedicated spot, or in a large container where its root spread is limited.

Can I grow fennel in a pot?

Yes, though fennel develops a long taproot and needs a deep container - at least 40 to 50cm deep and 30cm wide. Use a free-draining compost and water regularly during dry weather. Container growing also has the advantage of containing fennel's allelopathic root chemicals, so it won't affect neighbouring plants.

Is fennel perennial in the UK?

Yes - herb fennel is a hardy perennial and will survive UK winters, dying back to the ground before returning in spring. In mild years or sheltered positions it may remain partially green through winter. Cut old stems back in late autumn or early spring. Well-established plants become increasingly productive and long-lived.

How do I stop fennel self-seeding?

Fennel can self-seed prolifically if the flower heads are left to mature. To prevent this, deadhead the umbels as soon as flowering is finished but before the seeds ripen and fall. Alternatively, cut the whole flower head and hang it upside down in a paper bag over a bowl - this way you collect the seeds for cooking rather than losing them to the soil.

Can I use fennel flowers as well as the fronds?

Absolutely. Fennel flowers - the small yellow blooms that make up the flat umbels - are edible and delicious. They have the same anise flavour as the fronds but lighter and more delicate. Use them as a garnish for fish dishes, scattered over salads, or floated on top of a cold soup. They also look stunning in a herb bouquet.