I used to think cauliflower was a tricky customer to grow – a bit of a diva! But once I got to know this very special brassica, I realised it’s not that difficult after all. In fact, follow the tips I’m about to share and you can look forward to truly exceptional cauliflowers every time!
Cauliflowers and Their Relatives
Cauliflowers are one of the very finest vegetables you can grow thanks to their spectacular versatility in the kitchen. But did you know that most of the brassicas (cabbage-family crops) we grow all come from the same wild cabbage, Brassica oleracea – each vegetable bred over many centuries for a particular trait. This never ceases to amaze me!
Get this: cabbage? Basically, a super-enlarged terminal bud. Kohlrabi? A swollen, edible stem. Broccoli has enlarged, immature flower heads and stalks. And then there’s cauliflower with the beautiful, dense, tightly closed whorls of flower buds. It’s remarkable when you think about it!
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Not all cauliflowers are white!
And did you know you don’t have to settle for white cauliflowers – there are green, yellow, orange and even purple varieties available – honestly, they have to be seen to be believed! Absolute beauts!
How to Sow Cauliflowers
Cauliflowers can be sown directly where they are to grow, but this is quite a space-hungry vegetable, so taking up precious ground space while they’re still at the seedling stage just doesn’t make much sense. Far better to sow them into plug trays I say!
If starting them in autumn choose a particularly hardy variety that’ll happily overwinter for planting out next spring. This will give the very earliest cauliflower harvest next season – something to look forward to as the nights start to draw in. This is a truly delicious opportunity to get ahead while most other crops are winding down!
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Cauliflowers can be sown over a long period
I like to use a plug tray to sow into. Fill the plug tray with multi-purpose potting mix, and then sow two seeds per plug. Firm down the potting mix with your fingertips, and pop in your seeds. Cover them over with a bit more potting mix so they’re at least a quarter inch (0.5 cm) deep. Then let’s finish with a good water to get them on their way.
I keep my cauliflowers in the greenhouse over winter, to be transplanted early next spring. Once they’ve germinated, I’ll remove the smallest or weakest seedling to leave just one per plug. If you don’t have a greenhouse, then a cold frame would work well, or any sheltered spot that’s protected from pests like slugs and pigeons (more on those ne’er-do-wells in a bit!).
If you’re sowing an expensive packet of seeds by the way – some only come with a couple of dozen seeds – then an alternative to sowing two seeds per plug is to sow into a pot of potting mix, then once they’ve popped up, transfer the seedlings to their own plugs – one per plug. This way you’re not wasting any precious seedlings.
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Cauliflower seedlings germinate rapidly, even at cooler temperatures
Like other brassicas, cauliflowers can grow at surprisingly low temperatures – as low as around 45ºF (7ºC) – so if you get a mild winter there’s a good chance the seedlings will grow well enough to fill their plugs, so you may need to move them on into larger plugs or pots, depending on how big they get, And that’s my number one tip for cauliflowers – we don’t want plants to be held back at any point; the aim is to keep plants growing seamlessly.
I won’t be sowing any more cauliflowers over the winter months, but will start again from early spring. And because plants sown on the same date tend to reach maturity at the same time – stands to logic, right? – I’d say it’s worth making regular sowings from spring to spread out the harvest and the joy of those delicious heads, perhaps sowing a batch every two to three weeks, depending on how much you love your cauliflower of course!
When you can sow will vary according to variety and, of course, where you’re growing. You can get a timetable tailored to your exact location using our Garden Planner.
It’s pretty clever really, because it uses data from your nearest weather station to work out ideal growing dates… Nice!
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Pot on or plant out cauliflower seedlings at the right time to avoid holding them back
Planting Cauliflowers
Like most cabbage-family vegetables, cauliflower loves a rich, fertile and moist soil, so it definitely pays to add plenty of well-rotted manure or compost in advance of planting. A heaped bucket per square yard or metre should do the trick, which should give a depth of an inch or so.
Cauliflowers don’t grow well in very acidic soil, preferring a pH in the region of 6 to 7. Now please don’t worry – most soils are typically just fine, but if you do know that you’re gardening in an especially acidic area, perhaps test the soil with an off-the-shelf pH testing kit, and if it’s much below 6, add something that’ll help to raise that pH – garden lime or, if you have access to it, wood ash, sprinkled over the soil ahead of planting.
Transplant young plants into their final growing positions once the roots have filled their plugs, or they have around two pairs of adult leaves. Set them around 18in (45 cm) apart in a block formation to give modest-sized heads, but for the biggest cauliflowers you’ll want to shoot for a spacing more like two foot (60 cm) apart. The seed packet for the variety you’re growing should give more guidance on the best spacings for that particular variety, so check that if in doubt.
To plant, dib a planting hole, pop in the young plant, and then backfill the hole, firming the soil around the root ball. And to finish, give it a good drink of water to settle it in.
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Caterpillars can munch leaves and infest cauliflower heads, so exclude them with netting
Cauliflower Problems to Sidestep
The first challenge that many cauliflowers face are the caterpillars of cabbage white butterflies. These hungry caterpillars can, in the growing season, strip back plants with ruthless efficiency. The best way to keep them off is with butterfly netting or something finer like insect mesh to be sure of keeping butterflies and moths off your plants.
Both of these covers will also keep birds off – particularly pigeons, which can also strip plants when your back’s turned, the scallywags! Keep butterfly protection in place from late spring, and pigeon protection in position for much of the winter and spring, depending on how determined they are in your area.
Another occasional pest is cabbage root fly. It looks a lot like a standard housefly and lays its eggs on the soil surface, right at the base of plants. It’s the maggots that cause the damage as they burrow into the roots, which can severely weaken or even kill plants. That’s the bad news. The good news is these flies aren’t especially clever, so it’s very easy to outwit them!
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Cabbage root flies lay eggs around the base of cauliflowers and other brassicas
Cabbage root flies appear from late spring and the simplest way to beat them is to position collars around the base of the stems – either purpose-sold ‘brassica collars’ or, cheaper, your own homemade versions. I make my own by cutting a circle of old carpet or matting about 15cm (6 in) across. Cut a slit to the middle and then slip the collar around your cauliflower’s stem. The flies will still arrive and lay their eggs next to the stems, but because they’ll be laid on the collars, they’re likely to just dry out and fail, keeping your plants nice and safe. It’s a deceptively simple solution, right?! Or you could just use a fine insect mesh to keep the flies off altogether.
Once cauliflowers are planted and protected, there’s not much extra care needed other than pulling out the odd weed to minimise competition. Keep plants well-watered in dry weather – essential to prevent poorly-formed heads and to prevent them from bolting (when the heads open up and flower without giving those lovely dense heads).
To get the pearliest-white, sweetest heads, you can ‘blanch’ your cauliflowers once the developing heads reach about tennis ball size. Carefully bring the outer leaves together to cover the head, then tie or fold them in place so the head remains covered.
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A freshly harvested cauliflower is a beautiful thing to behold!
Harvesting Cauliflowers
So, the big question: when’s it best to harvest those pearly white (or otherwise) heads of intense goodness? I like to cut mine once they’ve reached somewhere between 6-8 inches, (15-20 cm) across. Use a sharp knife or pruners to cut the head and its surrounding leaves, which will help to protect the head and maximise how long it keeps for.
If you notice the heads are full of insects a little tip is to break the head up a bit, then plunge it into salt water for about half an hour. Not only will this help flush out any hidden bugs, it will also clean off any microbes and dirt, ensuring a fresher, cleaner head. Rinse the heads off in cold, running water, pat dry, then store in the fridge or blanch and freeze.
In my opinion you can’t beat a cauliflower and potato curry (aloo gobi), but I’ve heard there’s all sorts of things being done with cauliflowers – soups, purees, or cauliflower rice anyone? I’ll let you be the judge!
