Cauliflower is one of the more fussy members of the brassica family and can be more difficult to grow. Polytunnel growing could be the answer for those who have struggled to get good cauliflowers from their garden as a polytunnel can offer a more controlled growing environment where it is easier to keep on top of watering as well as pests and diseases. The main thing with cauliflowers is to make sure that there is no check to their growth which comes from cold snaps or inconsistent watering. This is where a polytunnel, perhaps especially one with an irrigation system, can really come into its own.
As with other members of the cabbage, or brassica, family, cauliflowers need a rich a fertile soil in which to grow and are nitrogen hungry plants. If the soil is too acidic then the pH will have to be amended in order to grow cauliflowers successfully. It is also important to choose the right cauliflower varieties for where you live as some types are not hardy and will only grow successfully in the warmest and sunniest parts of the UK.
Sow cauliflower seeds at a depth of around 1cm. Autumn and winter harvested cauliflowers can be sown indoors or with protection from February and until May. There are also summer harvested types that can be sown under cover from late September – November. It is very important to leave enough space for these hungry and thirsty plants to grow – there should be spacing of at least 90cm between plants for full-sized heads, or half that for 'one-person', individual heads.
As well as watering well and deeply on a regular basis, it is also a good idea to help retain soil moisture around cauliflowers with a good quality, organic, high-nitrogen mulch over the summer months and to companion plant around the edges of cauliflower beds with legumes to fix nitrogen and alliums and herbs to reduce pest problems.
If you have enough space to space and sow several different cauliflower types then you could be eating cauliflower from your garden or polytunnel almost all year round. If you are in any doubt about the fertility of your soil or your ability to prevent a check on growth then you might wish to grow other brassicas instead. Some sprouting broccoli, including a perennial type, is a cross between a cauliflower and broccoli in terms of look and taste and can be easier to grow at home. It is best to harvest cauliflower heads in the morning while still covered in dew – waiting until the frost has gone if it is winter. Do not leave the heads too long – it is better to harvest small than to harvest too late as cauliflowers will quickly spoil once the heads begin to open up and flower. Do not discard fresh green outer leaves – these are also good to eat.
Sow under cover – September
In heat – January
Outdoors – April
Cutting time – June to September
Sow outdoors – April to May
Cutting time – October to November
Sow outdoors – May
Cutting time – March to May