Sowing and Growing Cauliflower

What is Cauliflower?

Cauliflower is part of the brassica family, and the main edible part is the large central flower. There are many varieties that mature at different times of the year, generally sown in late winter and spring.

Why Grow Cauliflower?

While cauliflower is versatile and healthy, it does have significant downsides. It takes a long time to grow, can be tricky to cultivate, requires a lot of space, and its single flower harvest is easily affected by weather and pests. Unlike other brassicas, cauliflower doesn’t offer a notable leaf harvest, though some people do make use of the large leaves.

To offset these challenges, we grow a couple of successions of cauliflower in spring and autumn when we have more space, and focus on quicker-growing, more reliable flowering brassicas, like calabrese and purple sprouting broccoli.

How Many to Grow?

If you enjoy freezing cauliflower, you can grow as much as you like, as each plant produces one head. However, if you don’t freeze it, things get a little trickier. Cauliflowers tend to all mature at the same time, and if you’re lucky, they’ll hold in the ground for two weeks. For a small family, growing more than 0.5 plants per person per week might be too much, unless you love cauliflower! As a treat, you could grow two plants per month from March to June, requiring around 2m² of space. For larger families or those with ample space, grow 1m² per month.

Growing Conditions

Cauliflowers are demanding plants, needing plenty of sun, regular watering, rich organic matter, and pest protection. They are difficult—but not impossible—to grow in containers, though the yield might not be worth the effort in terms of space or cost.

Sowing and Harvesting Times

Supermarket cauliflowers might all look similar, but once you grow your own, you’ll discover their diversity! They have large, tough leaves, and come in beautiful colours like purple and green, as well as white. You’ll also find varieties with different shapes, such as the stunning Romanesco form. This variation also means they have a wide range of growing periods.

First Early Cauliflowers (Sown in Late September for Early and Late Spring Harvest)

Sow seeds in late September and early October. Start them indoors, then move to an unheated polytunnel in pots. You can plant them out in late winter or early spring, depending on the protection you provide.

Second Early Cauliflowers (Sown in January for Late Spring/Early Summer Harvest)

Start sowing in January with the help of grow lights for the first few weeks. These will be ready to plant out in late February or early March, depending on the weather.

Main Crop Cauliflowers (Sown in Mid-February for Summer Harvest)

Sow mid-February, and the plants will mature by June.

Late Crop Cauliflowers (Sown in May for Autumn Harvest)

For autumn and early winter, Romanesco varieties are a great option. Sow these in May or June.

Winter Cauliflowers (Sown in June for Winter Harvest)

We don’t recommend winter cauliflowers due to their space demands and relatively unreliable harvest. Early varieties of purple sprouting broccoli tend to be a better option for winter, offering a continuous harvest and a good supply of leaves.

Recommended Varieties

Cauliflowers come in many varieties, and the seed packets often offer a wider range of sowing dates than we recommend. Feel free to experiment!

Sowing Tips

Sow seeds about ½ inch deep in module trays and water lightly. Once germinated, prick out the seedlings into individual modules before their true leaves form.

Where to Plant Cauliflower

Cauliflowers thrive in full sun or light shade, with more sunlight leading to a larger harvest. The soil should be firm, but it's not necessary to walk on it; simply firming in individual seedlings as you plant them is usually sufficient. Ideally, cauliflowers prefer neutral to slightly alkaline soil for optimal growth.

How Many to Plant

Cauliflowers are quite adaptable when it comes to planting density. The spacing you choose will influence the size of the heads. For smaller heads and leaves, experiment with planting 12-14 inches apart. For larger heads, aim for 18-24 inches between each plant.

Planting and Care

Plant in full sun or light shade. Cauliflowers like firm soil, but there’s no need to walk on it—just firm in the seedlings as you plant. Ideal spacing is between 12-24 inches, depending on the size of heads you want to harvest.

Feeding and Watering

Mulch with 2 inches of compost before planting, and water well. Provide about 1 inch of water weekly once the plants are established.

Harvesting and Storing

Harvest before the florets begin to spread, though don’t worry if they do. Cauliflowers store well in the fridge in a loose plastic bag for a few days. We often mix purple and white florets with leaves for a fresh brassica box.

Cooking Tips

Cauliflower can be cooked in many ways—roasted, boiled, or mashed, for example. It’s so versatile that we often make cauliflower rice, which is a great way to use flowers that don’t look supermarket-perfect!

Pest and Disease Management

Cauliflowers benefit from protection against pests. Use fleece for early crops and netting to deter birds and butterflies for main and late crops. Keep an eye on them for any fungal infections and remove affected leaves.

Removing Cauliflower Plants

Once your cauliflower has been harvested, it's best to cut the stem just below the soil surface using large pruning shears. The roots can be left in the ground to decompose naturally, helping to improve the soil structure.

What to Plant Before Cauliflower

It's important to avoid planting brassicas immediately after other brassicas. The crops you plant before cauliflower depend on the timing of the succession:

What to Plant After Cauliflower

After harvesting your cauliflower, be mindful to avoid following brassicas with other brassicas. Here's what to plant depending on the succession:

Interplanting with Cauliflower

Early cauliflower is often relay-planted into other beds rather than interplanted. However, if your cauliflower beds are widely spaced with open ground, consider interplanting with quick-growing crops like radish or turnips. Cauliflower’s large leaves will eventually spread, limiting the space available for interplants.

Interplanting isn't just about filling gaps—it's about creating a partnership between crops that benefits both. Consider the following when interplanting:

1. Does one plant enhance nutrient availability for the other?
2. Does one help protect the other from pests or diseases?
3. Do the plants have different root depths, allowing them to access water and nutrients at different levels?
4. Do they grow at different rates, so one can be harvested before the other needs the space?
5. Does one plant provide shade or wind protection for the other?
6. Is one plant a backup in case the other fails?
7. Does one plant deter pests or attract beneficial insects (though many of these ideas are more myth than fact)?