Sow thinly, 2cm (¾in) deep in a seedbed. Final rows should be 15cm (6in) apart for mini caulis or around 60cm (24in) for larger cultivars. Thin the seedlings to a final spacing of 15cm (6in) apart for mini caulis or 60cm (24in) for larger cultivars. However, best results come from sowing in cell trays using any good multi-purpose potting compost. As cauliflowers mature in a rush, avoid raising too many plants at a time.
The main sowing period is March to May, although early crops can be achieved by sowing under glass in January/February or sowing cultivars in the autumn in a glasshouse or coldframe.
Cauliflowers do best in very fertile soil, and digging in a bucketful of well-rotted manure or organic matter before planting, and raking in 150g per sq m of Growmore or other general purpose fertiliser, will help growth. Firm the soil by treading before planting.
If growth is checked, at any time during growth, they produce small, deformed heads. To avoid problems, water plants well the day before transplanting and make a hole deep enough to hold the plant with the lowest leaves at ground level. Fill this hole repeatedly with water. This will fill the hole with soil and ensure the plant is sitting in a large area of moist soil. Firm the soil very well against the roots.
Space summer and autumn cropping types 60cm (2ft) apart and winter cultivars around 75cm (2.5ft) apart; spacing of 30-45cm (12-18in) apart, provides mini, 'one person' curds.
Water well in dry weather, watering every 10 days, and apply sufficient water to thoroughly wet the root zone. Once the plants are growing well, add 30g (1oz) per square metre of high nitrogen fertiliser such as sulphate of ammonia to boost growth and curd formation.
Birds: Birds, especially pigeons, can cause an array of problems including eating seedlings, buds, leaves, fruit and vegetables.
Remedy: Protect the plants from birds by covering them with netting or fleece. Scarecrows and bird-scaring mechanisms work for a while, but the most reliable method of protection is to cover plants with horticultural fleece or mesh.
More info on Birds
Club root: Roots become swollen and distorted, and leaves become pale and yellow and wilt easily. Plants may die.
Remedy: Improve drainage and add lime to make soil more alkaline. Do not grow in affected soil.
More info on Club root
Caterpillars: A number of caterpillars will feed on brassicas, but the most common are those of cabbage white butterflies. You will usually see the caterpillars, if not, you will see the holes they make in the leaves. They will also bore into the heart of cabbages.
Remedy: In mild attacks, or if you have only a few plants, you may be able to pick the caterpillars off. You can spray with pyrethrum, deltamethrin or lambda-cyhalothrin. Insect-proof mesh or fine netting (5-7mm mesh) can prevent egg-laying.
More info on Caterpillars
Start cutting when the heads are firm; once the florets start to separate, it is too late.
‘Cheddar’AGM: Has orange-yellow flower-heads.
Skywalker’ AGM: Autumn use with particularly large white curds.
‘Clapton’: With large, white heads, this is for summer to late autumn harvest. Club root resistant.
‘Graffiti’AGM: Has deep purple heads.