Cauliflowers are members of the brassica family and the name comes from the Latin words caulis, for cabbage, and floris, for flower.
It has the reputation of being a temperamental crop to raise so it is probably not one for beginners to try, unless you like a challenge! Each cauliflower produces a single head which means you just have one chance to get it right.
Shop bought cauliflowers are generally creamy white but grow your own and you can enjoy yellow, green, or even purple curds.
To successfully grow cauliflowers, you need to know about:
Cauliflowers do best in very fertile soil, so dig in some well-rotted manure or organic matter a few months before planting if possible. Like all brassicas, cauliflowers like a firm soil so tread it in lightly before planting.
Cauliflowers thrive in temperatures around 16-18C, so a typical Scottish summer is ideal for them. If the temperature exceeds 24C, the plants have a tendency to button or bolt.
Best Time to Plant
There are three types of cauliflower: summer, autumn, and winter varieties meaning there are cauliflower varieties which can be grown all year round. By choosing different varieties to plant at different times, it is possible to have a cauliflower to cut most of the year.
Summer varieties can be sown in a cold frame in September, indoors in January, or outdoors in April and some varieties may be harvested around July while other outdoor sown varieties will be ready now during August.
Autumn varieties mature in October and November and winter cauliflowers will be ready to harvest in the hungry gap from March through to June.
The main sowing period is generally March to May, although early crops can be sown under glass in January or February or later cultivars sown in the autumn under cover. The best time to plant most varieties of cauliflower is in the spring so they grow and produce their flower heads before warmer summer temperatures.
Sow seeds thinly, 2cm (¾in) deep in a seedbed or in a seeds tray using a good multi-purpose compost if sowing under cover. This is a good crop to succession sow so you do not have a glut of cauliflowers all at the same time.
Cauliflowers take up quite a bit of space and summer and autumn cropping types should be planted 60cm (2ft) between plants and 60cm between rows. The distance between the plants will determine the size of the head: the closer you plant, the smaller the head.
Yellow, green, and purple cultivars need sun to develop their colour, but do not allow too much sunlight to get onto the head of white cauliflowers as it will cause the curds to be slightly yellow rather than white. White cauliflower should be blanched: when the head is tennis ball size, fold or lightly tie the outer leaves over the developing head to shade it and keep it from turning yellow.
Cauliflowers are very hungry plants and need plenty of nitrogen to grow well and boost curd formation.
Water well in dry weather, especially in summer, making sure the roots get sufficiently soaked.
Cauliflowers are loved by pigeons, slugs, and caterpillars. Pigeons will eat the leaves of young plants, slugs will scale the stem and eat away the surface of curds leaving brown trails, and caterpillars will eat the leaves and get into the curd.
Additionally, as cauliflowers belong to the brassica family, they are susceptible to all the same diseases like cabbage root fly, cabbage white caterpillars, cabbage whitefly, and clubroot:
- The caterpillars of the cabbage white butterfly will decimate your plants to a stalk within a couple of days, so look out for yellow eggs under the leaves and pick them off. The best method to prevent them landing is to cover your crop with fine mesh.
- The Cabbage whitefly is an aphid which produces a sticky substance called honeydew which will cause grey mould later. Check for tiny white insects on the underside of the leaves and remove yellowing leaves at the base of the plant which might be harbouring aphid eggs. A strong jet of water will wash off most whitefly, honeydew, and grey mould.
- Cabbage root fly is a small grey fly which lays eggs at the base of cabbage seedlings. Maggots hatch from the eggs and burrow down, feasting on the new roots of your brassicas. Plants will begin to wilt and stop growing. Cabbage collars can be fitted around the base of plants to stop the fly laying its eggs but covering with a fine net is also advisable. You could also apply nematodes which are a biological control, mixed in water and applied to the soil to increase this naturally occurring microscopic worm in the soil which attacks the larvae of the cabbage root fly.
- Clubroot is one of the trickiest diseases you will encounter in the garden, liking wet conditions. If your brassica leaves are a a reddish-purple colour and have poor, wilting growth, you could pull up a root to see if there is deformed, knobbly growth with a foul smell. Do not compost those roots, try to burn them and do not sow any member of the brassica family in that same spot. Clubroot likes acidic soil so you could add lime to the soil in autumn to make it more alkaline.
Cauliflowers are best eaten fresh when the heads are compact and firm. Typically, only the head is eaten but do check The Indonesian Cook’s recipe for using the leaves too.
They are ready to harvest a week or two after blanching or covering the heads. Check the heads every couple of days and harvest when the heads are 6 inches (around 15cm) across but before the flower parts begin to separate. If the heads are small but have already started to open up, harvest immediately.
Cut the cauliflower from the plant leaving at least one set of leaves around the head to keep it protected.
Cauliflowers can be stored in the fridge for 1-2 weeks wrapped tightly in cling film.
For long-term storage, you can freeze the heads. Cut into 1 inch pieces, blanch for 3 minutes in lightly salted water, then cool in an ice bath for 3 minutes, drain, seal, and freeze.
Varieties to Plant Now for an Early Spring Harvest
- ‘All Year Round’ is suitable for sowing in September and October, coping well in a range of conditions and produces a good sized cauliflower head.
- ‘Jerome F1’ fares well through the winter. It has deep, white heads for harvesting in April. The vigorous leaves should be folded over the curds to protect them from winter weather.
- ‘Chester F1’ is a strong variety to sow in autumn for harvesting in late April or early May.
- Awarded the RHS Award Of Garden Merit (AGM), ‘Gypsy’ can tolerate less fertile soil. It can be sown in October and overwintered in a cold frame to be planted out in March for an early summer harvest.