Have you always wanted to learn how to grow cauliflower? Excellent! This lovely vegetable is of the most versatile members of the brassica family. Like broccoli, cauliflower’s edible part is the flower bud. Rows of compact heads—either white or in eye-catching oranges and purples—is a magnificent sight in any garden.
These vegetables are happiest in a cool climate, and have an unfair reputation for being a difficult to grow. If you follow the advice in this guide, you’ll soon be growing your own without any problems.
Before learning how to grow cauliflower you’ll need to identify the best variety for you. They don’t form heads in warm weather, and can only tolerate a light frost. This means that you’ll have to select a variety that can mature in your climate.
If you enjoy a short spring or fall, select a fast-maturing variety. In contrast, gardeners who live mild or late winters can grow late-maturing varieties. If you live in a cold climate, e.g. USDA zones 5 and lower, then I would advise planting out transplants in mid or late summer for a fall harvest.
Even with these restrictions there are still many varieties to choose from. Here are some of the most reliable:
- Snow Crown F1: A quick-growing and maturing hybrid, with some frost tolerance. Ideal for short growing seasons.
- Snowball: Produces medium heads and a continuous, good yield throughout the season.
- Cheddar F1: A slow to bolt, attractive, orange variety.
- di Sicilia Violetta: A stunning purple heirloom variety with a distinctive sweet and nutty flavor.
- Romanesco Early: An attractive, easy-to-grow variety that produces crisp, lime green florets throughout the season.
How to Grow Cauliflower
Where and when to Plant Cauliflower
Cauliflowers do best in full sun positions, ideally receiving 6 hours a day. They will also grow in partial shade. They also like moist atmospheres and cool temperatures,—ideally 65-70℉. Anything warmer can trigger bolting. This can be avoided in warmer climates by growing quick-maturing varieties, or by planting in partial shade.
You can sow cauliflowers outside between March and May. Earlier crops can be sown under glass in January or February. In milder climates, some varieties can be started undercover in the autumn for an early harvest the following spring.
Sowing Cauliflower Indoors
Cauliflowers hate having their roots disturbed, which often happens during transplanting. Sowing into peat or paper pots allows you to transplant the seedlings in situ, leaving the roots undisturbed. The pots will then decompose as the cauliflower grows.
Sow 2 cauliflower seeds half an inch deep in each pot. This allows for the possibility that one seed may fail. If both germinate, remove the weaker seedling. Cover the seeds with a thin layer of compost and water with a gentle spray.
They’ll germinate when the temperature is around 70℉. A greenhouse or south-facing windowsill is fine, but in colder climates placing the pots in a propagator will encourage germination. Don’t let the pots dry out.
Germination takes around 2 weeks, and after 4-6 weeks, the seedlings are ready for transplanting.
Sowing Cauliflower Seeds Outside
These vegetables like well-draining soil. Rake the soil, or turn it over with a fork, before planting. This will break up clumps of earth and improve drainage. Working in organic matter or a general purpose fertilizer before planting will also help to improve the soil.
Sow the seeds thinly: no more than an inch deep. The space a cauliflower needs depends on the variety, but generally mini cauliflowers should be 6 inches apart. Larger varieties may need up to 24 inches.
Cover the seeds with soil and water in with a gentle spray. You’ll need to thin the seedlings out as they grow.
Like other tender plants you should harden off cauliflower seedlings before transplanting.
Water the seedlings well an hour before moving them. This helps to prevent the plant from producing small or deformed heads.
Place each seedling in a hole about half an inch deep: the lower leaves should sit just above the ground. Space your cauliflowers 18-24 inches apart, giving the outer leaves plenty of room to form. The exact spacing varies between cauliflower varieties, so check the seed packet before you start planting.
After planting, water the cauliflowers in.
Caring for Cauliflowers
Now that we’ve covered how to grow cauliflower, you need to know how to care for them.
Watering and Fertilizing
Water your cauliflowers regularly, and don’t allow them to dry out.
Once established, fertilize the cauliflowers with a high-nitrogen feed to encourage growth. Consult the product information to know exactly how much you should apply. You can also use an organic fertilizer such as kelp or fish emulsion.
Placing a thick layer of organic mulch around your cauliflowers will provide extra nutrients, encouraging growth.
Weed around your cauliflowers regularly. These interlopers don’t just deprive your plants of valuable water and nutrients: they can also overwhelm younger seedlings.
Blanching is one of the most important things to master when learning how to grow cauliflower.
You must blanch cauliflowers if you want them to remain white. Unblanched cauliflowers turn yellow-brown, which is their natural color. They’re still edible, but just a bit unappetizing to look at. Colored varieties don’t require blanching.
Cease watering when the cauliflower head reaches the size of a large egg. This helps to prevent rotting. Then, fold some of the larger leaves over the cauliflower head to prevent light from reaching it. Secure the leaves in place with string but don’t tie them too tightly. Allow some room for growth.
Alternatively you can blanch the cauliflower by covering the plant with an upturned bucket.
From now on water only around the cauliflower, not the leaves. You should also check under the leaves every day for harmful pests.
Harvest cauliflowers 12 days after blanching.
Common Pests and Diseases
An important part of learning how to grow cauliflower is being able to cure and prevent common problems.
Since they’re brassicas, cauliflowers are susceptible certain pests that plague that family.
Maggots of the cabbage root fly can quickly destroy the cauliflower roots, stunting growth and killing the plant. Similarly, cabbage white caterpillars can reduce a healthy cauliflower to a skeleton within a couple of days. Regularly check the underside of the cauliflower leaves for yellow eggs. If you find any, brush them away.
Although cabbage whitefly is a less destructive pest, it coats leaves with sticky honeydew. This then turns into a grey mould. Remove any yellowing leaves and wash away the honeydew with a strong jet of water.
Groundhogs and pigeons also target cauliflowers. A fence or a cage is the most effective deterrent for the former, and nets can deter the later.
Clubroot rarely affects new vegetable gardens. It usually arrives through infected transplants, and can stunt growth and cause leaves to turn a reddish-purple color and wilt. On lifting, you’ll discover swollen or deformed roots. There will also be a distinct, foul odor. Eventually the roots will collapse into a slimy pulp.
If you discover a clubroot infestation, completely pull up the affected crop and burn it. Clubroot cysts can survive in the soil for up to 9 years. You can’t grow brassicas in the affected area for this period. Prevent clubroot by growing in raised beds or liming the soil in the autumn to make it more alkaline (clubroot likes acidic conditions).
In contrast, leaf tip dieback or distortion is a common problem, usually caused by a lack of boron. It can be countered by applying a kelp or seaweed fertilizer to the soil.
Cauliflower Companion Plants
Many gardeners find that cauliflower, beans, and celery are a great combination. Beans and cauliflower together is a particularly useful combination, as both attract beneficial insects and deter pests.
Aromatic herbs like thyme and sage also deter pests while attracting bees and other helpful insects.
Good companion plants:
- Brussels Sprouts
Plants to Avoid
Peas can stunt the growth of cauliflower crops, as can tomatoes. While not directly harmful, strawberries can attract slugs. Avoid planting near strawberries unless you want to see your crop destroyed.
Harvesting and Storing Cauliflower
Harvest when the cauliflower heads reach a decent size, about 6-8 inches in diameter, and the buds are still tightly together. Small heads, that have already started to open up, wont improve and can be harvested.Discard any cauliflowers that appear coarse. They are overly mature and will have lost their flavor.
Cut off cauliflower heads with a sharp knife. Try to keep some of the leaves with the head for protection.After harvesting the main head leave the stem in the ground. The cauliflower will continue to produce little florets, similar to broccoli. You can harvest and eat these floretes.
You can keep cauliflowers in a refrigerator for up to a week. If you want to store cauliflowers for a longer period, you can either freeze or pickle them. Alternatively you can lift the entire plant and store it, roots, stem and head intact, in a cool, dry location.