Cauliflower: guide to cultivation & care

Sebastian
Sebastian
Sebastian
Sebastian

As a horticulture student I mainly studied crops and cultivation techniques. It fascinates me how many diverse plants can grow from small, nearly identical seeds.

Favourite fruit: blueberries, grapes, raspberries, pears
Favourite vegetables: mushrooms, peppers, kohlrabi, onions, garlic

Cauliflower has become a real staple vegetable in our diets. With the right care and attention, you can grow a delicious crop of cauliflowers in your own garden.

Ripe head of cauliflower
The flower sprouts are what we later use in the kitchen [Photo: Orest lyzhechka/ Shutterstock.com]

Cauliflower (Brassica oleracea var. botrytis) looks very similar to broccoli (Brassica oleracea var. Italica). And no wonder – the two brassicas are closely related. Here you can find out about cauliflower’s origins, how it grows and how to ensure an abundant harvest.

Cauliflower origin

Cauliflower is thought to originate from South West Asia, after which, it spread throughout Europe via Italy in the 16th century. Through centuries of selection, crossing and breeding, it has become the large, white vegetable we find today on our supermarket shelves. Now it is grown all over the world and is one of the most popular types of brassica. As the name cauliflower suggests, it is usually the clusters of flower sprouts that are eaten.

In the kitchen, cauliflower is an all-rounder: it can be boiled, roasted, and also eaten raw or even made into “cauliflower couscous”. It is rich in vitamin C, B-vitamins, fibre and other essential nutrients. But it is not just the cauliflower head that you can use in cooking. Discover what you can do with the leaves and how best to store them in our article on harvesting, storing and using cauliflower.

white green yellow orange and purple cauliflowers
Cauliflower doesn’t have to be white, in fact there are many colourful varieties out there [Photo: I Wei Huang/ Shutterstock.com]

How do cauliflowers grow?

It all starts with the cauliflower seeds. These little seeds are brown to black, round and about 2 mm in diameter. Cauliflowers are “dicots”, which means their seedlings form two baby leaves known as cotyledons after germination. Over time, they develop a very large root system, with the radius of the roots often exceeding the size of the plant above the ground. Dark green, elongated oval leaves grow from a thick but short stalk, which are slightly wavy at the edges. The height of cauliflowers varies from variety to variety and can be up to 1 m tall when fully developed. For cauliflowers to flower at all, it is important for most varieties to experience a slightly cooler period of around 10 to 14 °C for about 10 days when plants have four to eight leaves. This so-called vernalisation ensures the shift of focus from leaf formation to the establishment of flowering plants. Just two months later, the cauliflower head will sprout into flowerheads. These flowers are yellow or white with four petals arranged in a cross. After pollination, the plants develop elongated pods full of cauliflower seeds. Nowadays, more and more colourful varieties of cauliflower are gaining popularity. Why not have a go at growing some of these beautiful cauliflower varieties yourself.

Differences between cauliflower, Romanesco and broccoli

Romanesco (Brassica oleracea convar. botrytis var. botrytis) is also Romanesco cauliflower or Romanesco broccoli. It is a variety of cauliflower and contains more vitamin C than its relative. As the name Romanesco suggests, it is thought to have been cultivated in Italy, near Rome.

Spiral shaped Romanesco broccoli heads
Despite looking so different, Romanesco is actually a variety of cauliflower [Photo: J_K/ Shutterstock.com]

Broccoli is closely related to cauliflower, but genetically much more distant than Romanesco cauliflower. However, compared to white cauliflower varieties, broccoli is packed with more vitamins.

You can find out exactly where and how to plant cauliflower along with other helpful tips in our article on planting cauliflower.

How to care for cauliflower

When it comes to cauliflower care, there are a few things you can do to keep your plants happy and ensure a bountiful harvest. From watering and fertilising to protecting your plants from pests and diseases, here are the most important things to bear in mind.

light yellow cauliflower head
If the caulflower is not protected from the sun, it can turn yellow [Photo: Amam ka/ Shutterstock.com]

Watering cauliflower plants and fertilising

As cauliflower is a heavy feeder, it is important to provide it with plenty of nutrients. For fertilisation, we recommend using a slow-release fertiliser such as our Plantura Tomato Food, which helps promote a healthy soil life in addition to supplying all the essential nutrients to the plant. Work the fertiliser into the soil once when planting and a second time about two months later.

Cauliflower also needs a lot of water, so make sure to water your plants regularly, especially during dry periods. A lack of water can cause cauliflower to bolt or only form seed pods.

Tip: It is worthwhile to regularly loosen the soil between the rows and remove weeds. This will help in the formation of larger heads.

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Protect cauliflower from the sun

Plenty of sunlight supports the cauliflower during the growing phase. However, if there is too much sunlight before harvesting, you should protect the white heads. A good way to do this is to fold the surrounding foliage in half over the cauliflower head. This causes minimal damage to the plant and can prevent sunburn. If you do not cover the cauliflowers, they may turn yellow or purple, depending on the variety, but remain perfectly edible.

Common cauliflower pests and diseases

In the early stages of growth, the small cauliflower plants are particularly susceptible to pests and diseases. The most common soil-borne diseases of cruciferous plants (Brassicacae) such as club root (Plasmodiophora brassicae), black rot (Xanthomonas campestris pv. campestris) or Verticillium wilt (Verticillium longisporum) can best be prevented by crop rotation with a cultivation break of about three to five years in each location.

Cauliflower covered in cabbage whitefly
Cabbage whitefly is a common pest of cauliflower [Photo: Afanasiev Andrii/ Shutterstock.com]

Aside from soil-borne diseases, pests such as the large cabbage white butterfly (Pieris brassicae), cabbage whitefly (Aleyrodes proletella) and cabbage root fly (Delia radicum) cause trouble for cauliflowers. There is a wide range of biological control treatments available, although it is still important to detect the infestation at an early stage to treat the plants effectively. Otherwise, the pests can quickly do too much damage for the plant to fully recover.

Cauliflower bolting: what to do?

Your cauliflower can bolt for several reasons. One simple reason is harvesting too late – be aware that the cauliflower in your garden will not necessarily reach the same size as the one you get in the supermarket.

Reasons why cauliflower bolts:

  • Harvest time too late
  • Too little water
  • Cold shock when transplanted too early

All cauliflowers can still be eaten after they start to bolt and flower, but they begin to lose their usual, mild taste and consistency. The longer the plant is left to flower, the more bitter the cauliflower can taste.

cauliflower sprouting flower shoots
When cauliflower starts to bolt, it can be for a number of reasons [Photo: Nnchp29/ Shutterstock.com]

Cauliflower not forming a head: why and how to avoid this

You shower your cauliflower with care and attention for two months and it grows and thrives, but you notice the cauliflower is not forming a head. This probably happens more often than we would like in the home garden and is quite often because the cauliflower was doing too well, or rather that it was too warm. Flowering occurs in cauliflowers around the 8-leaf stage, but only if there is an average temperature of 10 to 14 °C for about ten days around this time. It is recommended not to grow cauliflowers in a greenhouse unless you are after the cauliflower leaves.

Tip: Cauliflower leaves can be roasted or made into a delicious green soup.

Large white cauliflower head
For cauliflower to form a head, it must not be too warm [Photo: Alexlukin/ Shutterstock.com]

Growing cauliflower in winter

Cauliflowers can tolerate short temperature fluctuations around 0 °C and can be planted as early as March, although a fleece covering is essential here. Depending on the variety and whether they have been hardened off, cauliflowers can even withstand temperatures as low as – 12 °C. The cultivation of winter varieties, which are ready for harvesting in April, can only really be done in warmer southern regions. In our climate, the last cauliflower varieties from autumn cultivation are harvested between September and November.

Cauliflower propagation

To collect seeds from cauliflowers for growing next season, the plants are deliberately left to bolt and form flowers, which then produce seeds. However, they need to start flowering around July, as it takes a while for the seeds to ripen. It is possible to collect your own cauliflower seeds, but often hybridisation and crossbreeding can occur if the flower is not isolated from other plants.

Another type of brassica with delicious flowerheads is broccoli. Learn how to grow your own broccoli at home.

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