Florence Fennel

Fennel is sometimes called a ‘root vegetable’. However, the bulb which interests us is actually a swelling above the main roots, in the fashion of kohlrabi and beetroot. It’s not a taproot, unlike carrot and parsnip.

This means it transplants very well, either from being sown in modules or in a seed tray, to prick out into modules.

• Seeds germinate in seven to ten days, with long and thin cotyledons.

Sowing time

Timing is the crucial thing to get right and centres on this understanding: Florence fennel flowers in early to midsummer.

This allows time (just), from a very early sowing, for bulbs to swell before the development of a flower stem inside them. Once a stem initiates, bulbs lose their roundness and become long, thin and fibrous, rather than juicy and soft.

1. Sow undercover, from early February on a windowsill to late February in a greenhouse with some warmth. Sowings in late winter give more time for bulbs to swell than slightly later sowings in early to mid-spring.
2. Then do not sow again until July or midsummer. In warm climates, you can even sow in the first week of August. It depends partly on when your first frost is, because bulbs suffer damage below about -2 ° C/28 °F.

Sowing method

Raising plants under cover works really well for both early and late sowings. The reasons are:

1. Early sowings can germinate and grow in warmth, at a time when they would not germinate outside. This allows sufficient time for bulbs to mature before midsummer.
2. The second sowings of summer can be raised as transplants at the same time as an early vegetable harvest is reaching maturity. This overlaps their two periods of growth, which increases your growing season.

Fennel seedlings can be pricked out, and they transplant successfully. Sow in one of two ways:

• Ether in a seed tray, from which you prick seedlings to 2.5 cm/1 in modules after seven to ten days.
• Or sow two seeds per module and then thin to the strongest (or leave two plants, for a clump of two medium bulbs rather than one fat one).

The first leaves are tiny, therefore direct sow only where you know there to be few slugs. Take the same precautions as for sowing carrots (Lesson 8, Course 3A), with no slug habitat nearby.

Pot on?

There is no need to pot on fennel, a hardy plant that survives well as a small transplant.

Transplant four weeks after sowing in early spring, while in late summer you can transplant just two to three weeks after the sowing date.

Transplant method

Module-grown plants often have long, thin stems, which sit well in deep planting holes. Just check that the first true feathery leaves are above surface level.

Spacing

Space at an average of 20 cm/8 in, with variations according to your desired harvest.

• Plants at 15 cm/6 in can give earlier and successive harvests of small bulbs. You must take an early harvest to thin the planting, allowing for many later harvests from the same planting.
• Space at 25 cm/10 in for harvests of large bulbs.

Between other vegetables

The small size of fennel transplants together with the feathery nature of their leaves, which do not grab too much light from adjacent plants, make fennel an ideal interplant in both early spring and late summer. Another positive is fennel’s speed of growth, after a slow start, similar to its relative the carrot.

See the photos below, showing how this works between early spinach and late cucumber.

For the latter, we transplanted between cucumber plants whose leaves, by mid-August, were dying of mildew. There is still time from such late transplanting to have tender bulbs of 160 g/6 oz weight by October and November.

Other vegetables between

A nice example is to pop transplants of dwarf French beans, beetroot or chard between fennel bulbs, as they mature in early summer. At first the new plantings look overshadowed, but perhaps the fennel is ‘nursing’ them, through the mycorrhizal network.

• After the fennel harvest, you twist out their main roots and the new plantings grow fast because they have already established.

I have also enjoyed success with sowing corn salad between fennel when they are about half grown. Corn salad grows slowly at first, but is well established when you harvest the fennel in mid to late autumn. It gives you salad harvests outside in winter (see Lesson 25).

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Fennel likes it moist, while also tolerating periods of dryness. During a dry spring it pays to water in May, as soon as you see bulbs starting to swell. Soil that is too dry can result in premature bolting.

Be sure to water new transplants in late summer. After that, they may not need much extra water, since they enter the water-hungry swelling phase from mid-autumn, when days are damper.

Extra mulch to retain moisture?

Only needed in arid climates, where you will also need to water a lot.

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How to judge readiness

Early growth during the first part of spring (March and April) is slow, but then accelerates as days lengthen through May. Suddenly you notice some lovely bulbs; a few may also start to elongate by early summer.

• From the year’s first sowings, bulbing and flowering are close together in time, as fennel bulbs move so rapidly from a phase of swelling to one of flowering.
• If you transplanted at close spacing, a first harvest could be just 90 days after the sowing date, followed by many more over the next four to five weeks.
• In autumn, harvests are leisurely because bulbs swell slowly, with no tendency to elongate and flower.

How to pick

My preference is to rotate the bulb and remove its main roots, rather than simply cut the woody stem just above ground level. The reason for this is that new and small shoots grow from the main stem when it’s left in the soil.

If you want new shoots (which will soon flower in summer), simply cut the stem – it needs a sharp knife.

• How much you trim the leaves and stem is entirely your choice – all of the plant is edible.
• You can eat the roots – they have a dense texture and agreeable flavour, but it’s a small harvest.

When to pick and how often

The harvest period in early summer is only brief, so harvest a bulb or two as soon as they are large enough to eat, from about late May. Don’t expect them to grow really fat – it’s better to eat them before flowering initiates.

• This gives a summer harvest period of two to three weeks, maybe four if the weather is cool and damp.
• Harvests in autumn are prolonged because of day length reducing and temperatures falling. They may continue as late as December if frost holds off, with no risk of bulbs flowering.
• If November is a mild month, they continue to fatten a fair amount, even in the short days.

Do however check for frosts in the weather forecasts. Cover plants with thick fleece before any freezing nights, unless it’s just a slight ground frost.

Storing

Another option, before frost in late autumn, is to harvest bulbs for storing. At temperatures below 10° C/50° F, fennel bulbs stay in good condition for two weeks. Beyond that they are still good to eat, except you need to trim off a couple of browning outer stalks before using them.

In summer, best keep fennel bulbs in the fridge, or as cool as you can. They stay usable for a week, while losing a little flavour and texture.

Saving seed

I have not tried this because of the space needed for several plants. From an early sowing, in a temperate to warm climate, it’s possible to have seeds by autumn.

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Which pests are likely, and when

As with its relative the carrot, fennel suffers carrot root fly, but rarely enough to harm the plants.

Slugs eat seedlings.

• You should not need to cover with mesh against insects.
• Lay fleece/row cover on top of seedlings, to protect early plantings from cool spring weather.
• Then use fleece in mid to late autumn, laid on top in the evening, before any forecast of slight frost.

Other possible difficulties

Adjust sowing dates to reduce the problem of bolting – this is the main difficulty.

Frost is more about being prepared than a problem per se.

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