Cauliflower

Light and exposure

Cauliflower wants sunshine, but not a furnace. An open spot, sunny in the morning and a little sheltered during the hottest hours, suits it well in our climate. Six hours of light a day are enough to form a fine head, provided the soil below stays cool.

In the Herve area, our rarely scorching summers are an asset: cauliflower dreads dry heat more than coolness. Give it a corner where the wind does not dry out the soil too much, and plan for the space it will take, a mature plant easily occupies 50 to 60 centimetres.

Watering

This is the crux of the matter. Cauliflower needs permanently cool soil, never dry, never waterlogged. Water regularly and generously, at the base, without letting the soil dry out completely between two waterings. Water stress, even brief, is enemy number one: the plant responds by forming a dwarf head, aborting, or bolting to seed all at once.

In high summer, count on a thorough watering every two to three days in open ground, more often in dry, windy weather. A mulch of grass clippings or straw at the base keeps the moisture in and saves you a lot of trouble. It is better to water less often but deeply than to trickle a little water on the surface every day.

Soil and repotting

Cauliflower calls for rich, deep and cool soil, well supplied with nitrogen and not acidic. Before planting, work in plenty of mature compost or well-rotted manure, it is a heavy feeder. Soil that is too light and dries out quickly, or too poor, will never form a fine head.

Transplant at the 4 to 5 leaf stage. Bury the young plant up to the first leaves, firm it well and water generously to bind the roots to the soil. Space the plants 50 to 60 centimetres apart. Here, liming in autumn or before planting raises the pH and helps: cauliflower hates acidic soils, and lime also holds back clubroot.

Temperature and humidity

Cauliflower likes it cool. It grows ideally between 15 and 20 degrees and tolerates heat above 25 degrees poorly, which makes the heads abort or run to seed. Our mild springs and cool autumns suit it very well. Winter varieties withstand light frosts, but a head caught by a hard frost is lost.

The dampness of our air does not bother it, quite the opposite. The real risk is not the cold but the dry heat of July and August on the summer varieties: cover the soil, water without fail. For winter varieties harvested from November to March, a well-formed head overwinters outdoors, especially if you fold a few leaves over it for protection.

Pruning and upkeep

No pruning as such, but one key gesture: blanching. As soon as the head reaches the size of an egg, snap or fold two or three large leaves over it to cover it. Sheltered from the light, it stays nicely white instead of yellowing or greening in the sun. A rubber band or a folded leaf is enough.

For the rest, keep watch and hoe. Remove the yellowed lower leaves, weed at the base without harming the shallow roots, and earth up slightly the tall plants that the wind shakes. A dose of nitrogen fertiliser at mid-growth supports head formation on slightly poor soils.

Pests and diseases

Cauliflower attracts the whole cabbage clientele. The cabbage white lays its eggs on the foliage and its green caterpillars devour the leaves in summer: inspect the undersides of the leaves and remove the egg clusters by hand. The cabbage root fly lays at the collar, its maggots gnaw the roots and make the young plant wilt: a collar of cardboard or felt laid flat around the stem at transplanting blocks the egg-laying. Flea beetles that riddle the leaves with holes and grey cabbage aphids in grey colonies round off the picture.

As for diseases, clubroot is the most feared in our damp soils: the fungus deforms the roots into galls, the plant yellows and does nothing. It survives for years in the soil. The defence comes down to two gestures: a long rotation of 4 to 5 years with no cabbage at all on the same bed, and liming that raises the pH, because the fungus hates chalky soils.

Propagation

Cauliflower is propagated by sowing, in a nursery bed or in pots, then transplanting. Sow shallow, at one centimetre, in a fine compost kept cool. Emergence takes about a week at the right temperature. Transplant once at the 4 to 5 leaf stage, this transplanting strengthens the root system.

Stagger the sowings to spread the harvest: February and March under cover for spring and summer varieties, April and May in a nursery bed for autumn, and winter varieties sown from late May to June for a late harvest. Saving your own seed is possible but tricky, because cauliflower crosses easily with other brassicas: it is better to start from bought seed each year.

Month-by-month care calendar

Green Hub tips

• Enemy number one is water stress. Water regularly and generously: a dwarf head or one gone to seed almost always comes from a lack of water at the wrong moment.
• For a nicely white head, snap two or three leaves over it as soon as it reaches the size of an egg. In the shade of its own foliage, it does not yellow.
• Lay a cardboard collar flat around the stem at transplanting: it stops the cabbage root fly laying at the collar and spares you maggots at the roots.
• Long rotation and liming against clubroot: never grow a brassica where one has grown in the last 4 to 5 years, and chalky rather than acidic soil.