CauliflowerBrassica oleracea var. botrytis

Cauliflower wants full sun, but not a furnace: an open bed, without root competition, where the soil stays cool deep down. Our deep loams are ideal; heavy clays suit it if well structured, dry sands far less so. Place it out of the prevailing winds, which dry out and destabilise the plants. Rotation is crucial: five years without any brassica, cabbages, turnips, radishes, rocket or mustard green manure, on the same bed, to avoid clubroot. The spot where last year's peas, broad beans, early potatoes or leeks grew is perfect.

Cauliflower is the hungriest of the cabbages. The previous autumn, spread five to six kilos of composted manure or mature compost per square metre, worked in to twenty-five centimetres with a broadfork. If your soil is acid, betrayed by moss and dock, lime lightly at the same time, one hundred to one hundred and fifty grams of magnesian lime per square metre: clubroot retreats and the calcium prevents browning of the head. A month before planting, fork over, work in a handful of wood ash or extra compost, then firm the surface with the rake: cabbages like a settled soil.

For a June-July harvest, sow in February-March under cover, at 15-18 °C, in a seed tray, then prick out into eight-centimetre pots. This summer crop is tricky here, as a cold snap in April makes the plants 'button', forming a tiny head. The autumn crop, the safest in Belgium, is sown in an outdoor seedbed from mid-April to the end of May, in rows ten centimetres apart, one seed every two centimetres, one centimetre deep. Winter varieties, harvested in March-April, are sown in May-June and demand a mild winter.

A good cauliflower plant is six to eight weeks old, with five leaves, a short thick stem and a dense root system. Thin the seedbed to five centimetres as soon as the seedlings are up or, better, prick each seedling out into a pot as soon as it has two true leaves, burying it up to the seed leaves. Keep the plants cool, in the light, watered without excess, under insect-proof mesh from day one: flea beetles and the cabbage root fly target young plants. A drawn, yellowed plant, or one that has suffered thirst in its pot, will head up badly whatever you do afterwards. Better to throw it away and buy again.

Plant from late May to mid-July for the autumn harvest, in overcast weather, in soil watered the day before. Space sixty centimetres each way, seventy for the large autumn types. Dig a hole with a trowel, bury the plant up to the first leaves, draw the soil back and firm hard with your fist or heel: a cabbage that moves in the soil does not head up. Water generously, three litres per plant, and form a basin. Immediately fit a ten-centimetre collar of cardboard or felt around the neck against the cabbage root fly, then insect-proof mesh over hoops.

Cauliflower is not an ideal balcony vegetable, but it succeeds in a container at least forty centimetres deep and thirty litres per plant, filled with potting compost mixed with a third of garden compost and well firmed. Place the container in the sun, sheltered from wind, and water every day in summer: the slightest drought stress compromises the head. A dose of diluted nettle or comfrey liquid every fortnight is essential. Choose a compact, fast variety such as Boule de neige or a mini cauliflower, planted in June for a September harvest.

Planting in poor or freshly manured soil, letting the plant dry out just once in July, planting too early a plant that will face cold nights: each of these mistakes is paid for with a tiny head, known as buttoning, or no head at all. Cramming the plants at forty centimetres gives fine leaves and heads the size of a fist. Forgetting the collar and mesh means losing the plants to the root fly or watching them devoured by the cabbage white in August. Finally, replanting cabbages every year on the same bed establishes clubroot for ten years: rotation is not negotiable.

Cauliflower does not forgive thirst. After planting, water every two or three days for two weeks. Then give fifteen to twenty litres per square metre once or twice a week in summer, at the base, in the morning, without wetting the foliage. A rain gauge helps you get it right: below twenty millimetres a week, water. While the head is forming, in September-October, stay very regular, as this is when a check in growth makes the head go loose or brown. A thick mulch halves the frequency of watering.

Three weeks after planting, once the plants have established, mulch eight to ten centimetres deep with straw, dried grass clippings or leaves, keeping the neck and collar clear. Feed every three weeks from July to September with nettle or comfrey liquid diluted to 10 %, one watering can for two plants. A handful of mature compost around each plant in August completes the feeding. Stop feeding as soon as the head appears. A boron shortage, common on limed soils, causes hollow stems and brown heads: a little manure compost and comfrey prevent most of it.

A month after planting, hoe then draw five centimetres of soil against the stem: the plant anchors itself and puts out extra roots. Repeat in August. When the head reaches the size of an egg, protect it from light, which yellows it, and from rain, which stains it: half-snap two or three large inner leaves and fold them over it, or tie the outer leaves over the top with raffia. Check every two days, as the head swells very fast, and replace the snapped leaves if they wilt. So-called self-protecting varieties take care of this themselves.

The cabbage root fly lays at the neck in May and August: a collar and deep planting are usually enough; a plant that wilts in full daylight and recovers in the evening is a victim, so pull it up. The cabbage white butterfly lays from June to September under the leaves: insect-proof mesh over hoops is the only reliable protection; without mesh, crush the yellow eggs every week and pick off the caterpillars. Mealy cabbage aphids are treated with soft soap diluted to 5 %. Against clubroot, a five-year rotation, liming and drainage. Against flea beetles on young plants, water often and cover.

In March, sow under cover for summer. In April-May, sow in a seedbed for autumn, under mesh, and prick out into pots. In June, plant the autumn cauliflowers, collar, mesh, water. In July, mulch, feed with plant liquid, earth up, watch for cabbage white and aphids under the mesh. In August, feed, earth up again, water without fail. In September, stop feeding, cover the emerging heads, water regularly. In October-November, harvest as they come, remove the mesh, protect the last heads from frost. In December, pull up the stumps and take them to a hot compost heap or the bin.

Cut with a knife, below the head, with two or three rings of protective leaves, as soon as the head is firm and white and the curds are still tight: two days too long and it opens up. Harvest in the morning. A cauliflower that is starting to go loose is still edible, but will not keep. To spread the harvest, plant three times, a fortnight apart, in June and July, and mix early and late varieties. In November, when frost is forecast, pull up the whole plants with their roots and hang them head down in a cool cellar, where the heads finish swelling for two or three weeks.