How to Grow Cauliflowers
Cauliflower is such a versatile vegetable - from on-trend steaks and wings to good old cauliflower cheese. It’s not the easiest of brassicas to grow, but with a little care and attention, you’ll be rewarded with the best cauliflower you ever tasted. Let us show you how.
Most common Cauliflower plant questions
When should I plant cauliflowers?
Cauliflower is best planted from early April through to July.
Keep your plants indoors until the last frost has passed and the temperature is consistently above 14℃.
How much sunlight do cauliflowers need?
Cauliflowers need to be planted in full sun.
This should be somewhere where they will receive 6-8 hours of sunlight every day.
What kind of soil do cauliflowers need?
Cauliflower needs firm, fertile, well-draining soil.
A good mix is 3 parts compost with one part topsoil, raked into the ground or mixed into pots.
If you can, it is a good idea to prepare the soil the autumn before by adding a layer of well-rotted manure to give the soil extra nutrients and to improve its texture.
How far apart should I plant cauliflowers?
Space cauliflowers 60cm apart in the ground.
If you are growing cauliflower in pots then a pot of 15-20cm in width and 15-20cm in depth will be large enough.
How to plant cauliflowers
Before planting cauliflower, ensure that the soil is well compacted.
You can do this by treading on it or firming it down with your hands.
Dig a hole large enough for the root ball to fit in, pop the plant in, and then backfill with your soil mix. Push in the soil firmly around the roots. Give a generous watering to help the soil to further settle around the roots.
Keeping the soil firm around the roots is important for cauliflowers as it prevents root rot and smaller growing heads.
How much water do cauliflowers need?
Cauliflowers need regular watering and the ground must be kept consistently moist.
During hot summer days this means watering the plant at least once a day. If you are unsure, touch the soil and if it is dry to the touch a fingernail down then give the plant a watering.
If cauliflowers do not receive enough water and nutrients (see below) then they will simply stop growing so it is important to ensure the soil is not allowed to dry out.
How to feed cauliflowers
Cauliflowers will benefit from a weekly feed of liquid organic fertiliser.
They need a lot of nutrients to form the heads, and so this will give them an extra boost. When the flower heads form you can switch to a feed high in potash such as organic liquid tomato feed to propel head growth.
Potash, or potassium, is one of the three main elements in fertilisers along with nitrogen and phosphorus. Potash in particular supports growth of flowers and fruit and so this feed is often increased as the fruits or flowers are beginning to form.
How to harvest cauliflower plants
Use a clean knife to cut the stalk below a few leaves.
Cauliflowers take around two months to mature. They will be ready to harvest when the heads are around 10-15cm across. You will want to harvest them before the heads begin to spread out and are still compact.
Use a sharp, sterilised knife or pruning scissors and cut the entire head off below a few leaves.
Common cauliflower plant problems
There are a number of pests and diseases that target cauliflowers, including birds, slugs, caterpillars and cabbage root fly. For this reason, it is recommended that you cover your cauliflower with a fine horticultural fleece to prevent possible damage. Read below for more information on individual pests and diseases.
Birds - especially pigeons - are fond of tearing up young cauliflower seedlings.
The best form of protection against these winged thieves is a horticultural fleece. A scarecrow may offer some help, but I swear these cunning birds are getting smarter every year, so make it realistic.
Cabbage root fly
Cabbage root flies look like small, grey houseflies.
They lay their eggs near the base of plants and the maggots then feed on the roots of brassicas, swedes, radishes etc. They will cause the plant to have stunted and poor growth and you may notice the leaves beginning to wilt.
A horticultural fleece offers the best protection against this notorious brassica scourge. To add extra protection against cabbage root fly you should also use a brassica collar which prevents the flies from laying their eggs at the base of the plant and eating it from below.
Check under the leaves of the young plant for eggs.
If you find any, wipe them off. More than likely they will be the eggs of the white butterfly, which will hatch into caterpillars and really damage the plant.
Again, a horticultural fleece will prevent the butterflies from landing near your cauliflower and laying their eggs. If any caterpillars do hatch, pick them off ASAP.