How to grow cauliflowers
One of the trickier members of the brassica family, temperature and timing are important factors in mastering the art of growing a cauliflower. Pull off one of the striking lime, violet or orange caulis generally only seen at fancy greengrocers, then you can officially call yourself a vegetable growing pro.
SOW AND GROW
Sow seeds: December to March in warm areas; November to January in cooler areas Transplant seedlings: March to May and August to October in warm areas; February to April and August to October in cooler areas Position: Full sun, six or more hours a day Harvest: 14 – 26weeks from seed.
GET STARTED
Caulis can be started from seed from early summer through to mid-autumn in warmer climates; and late spring to midsummer in cooler parts of the country.
Seedlings can be planted in autumn and from late winter to mid-spring in warmer regions; and from late summer to mid-autumn and again from late winter to mid-spring in cooler regions.
STEP-BY-STEP
Sow cauliflower seed direct at a depth of 5-10mm in well-cultivated soil, or start them off in trays of seed-raising mix inside in a sunny spot or a glasshouse. Keep newly planted seed moist and warm. Expect signs of sprouting in 7-14 days. Thin the seedlings and, if growing in trays, pot them on into larger pots if necessary, Transplant into the garden when the plants are about 10cm high. Cauliflowers are large plants and in the garden most cultivars need to be spaced about 40-50cm apart.
GROWING TIPS
Cauliflowers can be grown throughout Aotearoa, but plants only form good-sized curds in low temperatures. Prepare the bed with compost, aged manure and a bit of lime before planting. Keep well watered during the growing season; but direct water towards the rootzone of the plant rather than overhead where the curds are developing. Don’t overdo it with high-nitrogen fertilisers as these can lead to leafy plants with small heads. Side dress with a liquid fertiliser every two to three weeks.
Harvest when heads are firm to the touch. Don’t wait too long or curds separate and start flowering. If you harvest the main head but leave the stem and roots intact, a few smaller caulis will grow.
STANDOUT VARIETIES
‘Snowball’ is a fast grower, maturing around 12 weeks from transplanting. Grow it as amini cauliflower by planting it 30cm apart and harvesting when its heads are 10cm across. It’s also a great variety for a pot, as is ‘Mini White F1’, which has heads measuring 10-15cm. Just remember to water pots daily during hot weather. ‘Clapton F1’ has good resistance to club root. ‘All Seasons’ and ‘All Year Round’ can be grown throughout the year in cooler regions, but will need to be protected from butterflies.
For coloured caulis, go for lime ‘Green Macerata’, purple ‘Violet Sicilian’ (best served raw as the colour fades upon cooking), or orange-toned ‘Cheddar’ (available in punnets) which contains 25 times more vitamin A than traditional white caulis. ‘Romanesco’ is the most beautiful of them all, its architectural-looking spikes resembling chartreuse coral.
TROUBLESHOOTING
Protect cauliflowers, particularly seedlings, from slugs and snails with cloches or go on a slug hunt at night and carefully fossick through the leaves, remove them by hand and squash.
In warm weather, caulis are plagued by whitefly and white cabbage butterfly caterpillars. Protect plants, including trays of seedlings, with a physical barrier such as an old net curtain or horticultural mesh. You can also inspect daily and pick off cabbage butterfly caterpillars by hand. Remove whitefly by spraying plants with soapy water or blasting the undersides of the leaves with your hose regularly. This will discourage aphids too.
Avoid club root, the brassica fungal disease, by adding lime to your soil before planting and by rotating your crops every year.