There are as many reasons not to grow cauliflowers as there are to grow them. They are the most challenging of all the brassicas to grow and too often they either fail to make a curd at all or they make tiny curds that are more likely to lead to derision than cauliflower cheese! But, if you have had luck with cabbages then cauliflowers are the logical next step and harvesting your own is very satisfying. They need the same basic growing conditions as all the brassicas and have the same problems, and rather than repeat myself you can read about them here.
Because cauliflowers are not easy, it pays to tip the scales in your favour. Most cauliflowers are summer or autumn maturing and these are sown from February (under glass) until May. You will then get cauliflowers from late July till October, depending on sowing and planting time and the variety. You can also get spring-maturing varieties and these are sown in May and June but these have more problems because they have to withstand winter outdoors, and survive hungry pigeons. Unless you adore cauliflower and don’t have a freezer I would plant sprouting broccoli instead. And talking of freezers, one of the problems is that a sowing of cauliflowers will all mature at the same time and they do not stand well. Most modern varieties have outer leaves that cover the curd and keep it white – if exposed to the sun or allowed to get old they will turn cream. Most cauliflowers are in a state of perfection for no more than a week, about six and a half days more than a ripe pear!
Of course, not all cauliflowers are white. You can get green, purple and orange cauliflowers, which are, of course, more nutritious. These are just as easy to grow, as you can see below. All are summer/autumn-maturing.
Which brings us on to Romanesco with their incredible, fractal heads. Once again these are summer-autumn maturing.
With all these, to make life easier, this is another case when I would always grow F1 hybrids. They have the disadvantage of maturing simultaneously but they are easier to grow. The seeds are horribly expensive but you really don’t want more than 20 cauliflowers maturing the same weekend anyway.
It is just about time to sow the first cauliflowers, either in pots or cell trays indoors. Get the planting area ready. Cauliflowers are happy in clay and, like all brassicas, prefer a heavy, rich soil to a light, sandy one. They need plenty of nitrogen in the soil too. Never stress the plants or let the soil dry out or you will get tiny curds. Once the seedlings have two leaves they are ready to plant out. If the leaves go purple you need to liquid feed them because if they are waiting too long in their small pots they will get stunted and not do well once planted out. If you are not ready to plant out repot them into larger pots to keep them growing on well.
Cauliflowers have longer, narrower leaves than cabbages and are quite large plants. They should be spaced about 40cm apart in the rows. Because they are not rapid growers you could put a lettuce between each, which will be pulled up before the cauliflowers elbow them out.
You need to watch for caterpillars in summer and it may be worth covering with fleece unless you are happy to go round squishing the horrors.