Growing Cauliflower

Cauliflower is rightly considered the king of the brassica family. Its mild, almost nutty flavour makes it popular even with people who normally steer clear of cabbage. What we harvest is actually the unopened flower head of the plant, the so-called "curd". It sits nestled among large, blue-green leaves on a short, sturdy stem.

Besides the classic white cauliflower, there are now yellow, green and purple varieties that bring colour to your plate. A special variant is Romanesco with its fascinating spiral-shaped florets.

Cauliflower is low in calories but packed with vitamin C, vitamin K, calcium, magnesium and valuable mustard oils.

Cauliflower is best started as a young plant indoors and then transplanted into the bed. The pre-cultivation takes at least 30 days. You can start sowing indoors as early as February. Just cover the seeds lightly with soil. The optimal germination temperature is 18 °C. Once they've germinated, grow them on much cooler, at around 12 °C. After about two weeks, prick out the seedlings. Before planting out, harden them off for a few days.

Between April and July, young plants can go into the bed. If frost is still a risk, protect the plants with fleece. Direct sowing into the bed is possible from mid-April to the end of June, but in practice it's not quite as reliable as transplanting young plants.

For overwintering, plant the young plants out between mid-August and mid-September. Make sure you use winter-hardy varieties.

Space them 50 cm apart in the row. Plant the cauliflower deep enough so the soil reaches the cotyledons. A bit of lime in the planting hole helps prevent clubroot. A handful of horn shavings makes a good slow-release fertiliser.

When it comes to choosing a spot, cauliflower is quite fussy. It thrives best in a sunny position, though light shade during the hottest hours of the day is fine. Very sunny, dry spots don't suit it well.

Soil preparation is key to success. The soil should have a loose structure and be deep enough for the roots to develop properly. The soil's ability to retain moisture is particularly important. Loamy soil meets this requirement perfectly. The soil should also be rich in humus, as cauliflower is one of the most nutrient-hungry vegetables.

An often underestimated factor is the lime content. A pH value between 6 and 7 significantly reduces the risk of the dreaded clubroot. Generous compost additions of around 5 litres per square metre prepare the bed perfectly and meet the high nutrient demands of this demanding crop.

There's a decent selection of cauliflower varieties that differ in head shape, colour and planting time. For getting started with this already somewhat demanding plant, 'Neckarperle' and 'Erfurter Zwerg' are good choices.

If you want to bring colour to the bed, try purple varieties like 'Di Sicilia Violetto' or choose the bright orange 'Sunset' for autumn growing.

For earlier or later planting times, there are special varieties — it's worth taking a closer look. For overwintering in milder regions, there are cultivars that can withstand frosts down to minus 12 degrees.

Right after planting, the young plants need a good watering. After that, water more sparingly for about three weeks so the roots grow deep into the soil. If cauliflower doesn't get enough water, the heads stay small or the plant bolts prematurely.

Diluted nettle feed or horn shavings work well for feeding during the growing season.

To stop the cauliflower head turning yellowish, it needs some sun protection. If the inner leaves don't fold over the curd on their own, simply snap a few over to provide shade.

An important point for head formation: at the four to eight leaf stage, the plant needs temperatures around 12 °C for about ten days. Without this cooling phase, no head will form. That's why growing in a warm greenhouse usually doesn't work.

Sadly, cauliflower is not only popular with us humans but also with all sorts of pests. Cabbage white caterpillars, cabbage root fly, cabbage whitefly and flea beetles can make your gardening life hard. The best prevention is a fine-mesh insect net that you stretch over the plants right after planting.

The swede midge is a particularly nasty pest. It lays its tiny eggs deep between the developing flower buds. You can spot affected plants by their twisted heart leaves. Growing in open, breezy spots and using close-mesh nets with a 0.8 mm mesh size help to prevent it.

Black rot is another disease dreaded on cauliflower. This bacterial disease causes yellow to brown V-shaped patches starting at the leaf edge, and the leaf veins turn black. It arrives with the seed or survives in old cabbage stumps and spreads in warm, wet weather through splashing water. Use healthy seed, water from below and clear away the stumps after harvest.

The slime mould Plasmodiophora brassicae causes clubroot. The signs are stunted growth and bluish discoloured or yellowing leaves. If you suspect it, dig up a root and check: it will show white, tuber-like swellings. If it really is clubroot, lift the whole plant with its roots straight away and put it in the household waste. Not on the compost, or you will spread the fungus further. From then on you need a break of at least 7 years for all brassicas on that spot. Add extra lime to raise the pH value.