Crops › fennel bulb
How to grow fennel bulb
in the UK
Sow April to July, harvest August to October. About 90 days from seed to plate.
Fennel's a bit of a cracking one, you know, makes a proper statement on the plot with its feathery leaves. It’s not the easiest veggie, like, but get it right and that aniseed flavour is just something else, especially fresh from the soil. Definitely worth the effort for something a bit different.
Sowing
Fennel likes to go straight into the ground, to be honest, so sow outdoors from April right through to July. You want to make a drill about 1.5 cm deep and sow your seeds thinly. Space them out about 15 cm apart once they're up and growing, with 30 cm between rows. Keeping them moist is key from the start, it stops them thinking about bolting too early. You can sow a small batch every few weeks for a continuous harvest, like I say, right up until the end of July. If you're buying plug plants, they'll save you a bit of faff, just plant them out when the weather's settled.
Growing on
If you did start any indoors, which I don't really bother with much for fennel, you'd want to harden them off gradually before planting them out. For outdoor sown or plug plants, make sure they have plenty of room, that 15 cm spacing is crucial for good bulb development. They don't need any special support, just good, rich soil. You can grow them in big containers too, mind, if your plot's a bit full or you've only got a patio.
Looking after it
The main thing with fennel is keeping it well watered, especially as the bulbs start to swell. Drought stress is a surefire way to make them bolt, so don't let the soil dry out. As the bulbs grow, gently earth up around them. This keeps them nice and white, and protects them a bit from the sun. No real need for extra feeding if your soil's decent.
What goes wrong
Slugs can be a right nuisance when the seedlings are small, so keep an eye out and use your preferred method to deter them. Aphids can sometimes gather on the tender new growth, but a good blast of water usually sorts them out. The biggest problem, to be honest, is bolting, which is when they flower instead of forming a bulb. Keep them watered and don't let them get stressed.
Harvest
Your fennel should be ready to harvest about 90 days after sowing, so from August onwards, right through to October. You want to pick them when the bulbs are about the size of a tennis ball. Just cut them at soil level with a sharp knife. They're cracking eaten fresh, that's definitely when they're at their best. If you've got a few, they'll keep for a couple of weeks in the fridge.
I always try to plant some lettuce nearby, or a few cucumbers, as they're meant to be good mates with fennel on the plot. It's a bit of a medium difficulty one, this, so don't be chuffed if your first go isn't perfect, just keep trying!
Dates for your plot
Type the first half of your postcode and the plant-out advice shifts to your area's typical frost dates.
Varieties, and whether the club would grow them again
| Variety | Club verdict |
|---|---|
| Zefa Fino This one's a good early option, reliable and doesn't rush to bolt on you. If you're keen to get an early crop on your plot, Zefa Fino is a cracking choice. | No club votes yet |
| Romanesco A proper traditional Italian variety, with that classic fennel flavour. Great for those who appreciate heritage varieties and want an authentic taste. | No club votes yet |
| Perfection This maincrop variety lives up to its name, producing nice large white bulbs. Ideal for a good steady harvest through late summer and early autumn. | No club votes yet |
| Cantino Cantino is a modern variety that's pretty robust and resists bolting well, which is always a bonus. You'll get a good yield from this one, making it a reliable choice for your plot. | No club votes yet |
| Victorio F1 If you're after a harvest later in the season, Victorio F1 is designed for late summer picking. It's a good one for extending your fennel supply into autumn. | No club votes yet |
| Finale Finale is brilliant for autumn harvesting, especially if you want to store some bulbs. It's an excellent choice for keeping that lovely aniseed flavour a bit longer. | No club votes yet |
| Cantino F1 This is a cracking maincrop F1 variety, known for producing proper large white bulbs. It's a solid, reliable choice for a good harvest on your allotment. | No club votes yet |
| Mammoth True to its name, Mammoth produces some seriously large bulbs, a proper heritage stunner. If you like your fennel big and bold, this one's for you. | No club votes yet |
| Florence Florence is a classic Italian variety, the sort of fennel you'd expect to see in a Mediterranean market. It offers that authentic taste and traditional growth. | No club votes yet |
| Selma Selma is a really dependable maincrop, giving you uniform and reliable bulbs every time. It's a cracking choice if you want consistency from your fennel patch. | No club votes yet |
| Solaris F1 Solaris F1 is a modern hybrid that's got good bolt resistance, which is always a relief on the plot. It's a reliable performer, even if the weather turns a bit unpredictable. | No club votes yet |
| Romy F1 Romy F1 is an excellent early variety, producing compact bulbs that are ready quickly. It's a good one for getting a prompt harvest from a smaller space. | No club votes yet |
| Sirio Sirio is a cracking late variety, giving you good, large bulbs towards the end of the season. Perfect for extending your fresh fennel supply right into autumn. | No club votes yet |
| Sweet Florence This heritage variety, Sweet Florence, is known for its incredibly sweet and tender bulbs. It's a delightful choice if you're after a particularly delicate flavour. | No club votes yet |
| Mantovano Mantovano is another classic Italian heritage variety, notable for its slightly flattened bulbs. It's a bit different and offers a lovely traditional taste from your plot. | No club votes yet |
Votes are members rating varieties in their Seed Tin, one vote per gardener. Tap a variety for the full page and where to buy.
Buy fennel bulb seeds
Partner retailers. If you buy through these links we may earn a small commission. It never costs you more.
Cook the harvest
A proper savoury tart where thick slices of fennel are slowly cooked down until deeply golden and sweet, then laid over a rich Gruyère custard in a buttery shortcrust case. The anise notes of the fennel mellow entirely in the pan, leaving something almost jammy and intensely savoury. This is the kind of thing worth making on a weekend afternoon — it rewards patience and it is stunning.
105 min · mediumThis Sicilian-style salad is one of the best things you can do with a fennel bulb and it takes under 20 minutes from start to plate. Thinly shaved raw fennel has a crisp, refreshing bite that pairs brilliantly with sweet autumn oranges and briny olives, all dressed in nothing more than good olive oil and a little salt. It works as a punchy side dish or, piled onto bruschetta, as a starter.
15 min · easyBone-in chicken thighs braised low and slow in a fragrant tomato sauce loaded with fennel, saffron and white wine — this is sunshine in a pot. The fennel breaks down into silky, yielding pieces that absorb all the cooking juices, and the saffron turns the sauce a deep golden amber. Serve over couscous or with crusty bread to mop up every last drop.
85 min · mediumThick slabs of fennel are roasted until caramelised and sticky under a deeply savoury miso and mirin glaze, then served over cold sesame soba noodles with cucumber and spring onion. The fennel's anise sweetness plays brilliantly against the umami-rich glaze, and the whole thing comes together in under 30 minutes. It is the kind of weeknight dinner that feels far more considered than the effort involved.
28 min · easyWatch for, and grow alongside
Questions people ask
When do you sow fennel bulb in the UK?
Sow fennel bulb from April to July.
How long does fennel bulb take from sowing to harvest?
Roughly 90 days, with the harvest August to October.
Which fennel bulb varieties do gardeners grow again?
Club members rate every variety they grow. This page shows the grow-again votes for Zefa Fino, Romanesco, Perfection, Cantino and more.
Track your fennel bulb from packet to plate
Sowing reminders and harvest forecasts for your own frost dates, the Seed Tin, Scan Centre for any label or packet, and the Potty Mouth Garden Club. Free to start.
Allotment keeper in the North East of England, the voice behind the Tony C Smith YouTube channel, and the gardener who built GrowMore CookMore. Club numbers on this page update as members log their plots. Last updated 3 September 2026.