Introduction
Mark Twain is said to have commented that ‘Cauliflowers are cabbages with a college education’. It is certainly true that Cauliflowers are more ‘demanding’ than the lowly cabbage. They are probably the most difficult of the brassica family to grow successfully, and accounts for the only limited success of many amateur growers.
Part of the problem may be attributed to the fact that there are four/five different groups of cauliflowers, each group having its own particular quirks. The other part of the problem is failure to recognise that cauliflowers generally ‘demand’ a greater degree of husbandry than other brassicas.
Like many brassicas, cauliflowers are biennials, and although certain varieties have been developed to initiate flowering more quickly than others, they grow vegetatively for a fairly long period. Then having reached a sufficient degree of maturity they will flower and go to seed quite quickly. As the ‘curd’ of the cauliflower is the head of flower buds, it has already achieved a high degree of maturity before it is ready to harvest, and unless the grower moves to harvest the curd at just the right time, the cauliflower can ‘go over’ in as little as 24-48 hours. Although cauliflowers can be variable in the timing of their maturity, with summer cauliflowers, especially in warm weather, they should be checked 3-4 times a week. Winter cauliflowers should be checked at least weekly. While cauliflowers can be stored for upto a week in a refrigerator, or can be deep frozen, it is better to avoid a glut by successional sowings.
Cauliflowers are big plants, with an appetite and thirst to match, and a need for room to grow. They need a rich deeply dug soil that has good moisture retention properties that will not dry out too quickly, but nevertheless has good drainage. Well-rotted farmyard manure can be added to the soil to improve structure and moisture retention. A pH of 6.5 - 7.0 (or slightly higher), should be aimed for, to discourage club root disease. This may be achieved by the addition of lime, though this should never be added at the same time as farmyard manure. If farmyard manure is deeply dug into the soil during autumn, then the application of lime to the surface should be left until late winter, allowed to wash in and then worked into the planting bed, as it is prepared. Alternatively, the lime can be added to the surface in the autumn, allowed to wash in, and well-rotted manure dug in during early spring. It can take up to 12 months for the lime to take full effect in reaching the desired pH, and thereafter its effect will gradually decline over subsequent years. It is preferable to grow cauliflowers, like all brassicas, as part of a crop rotation plan, and not replant in the same soil at a frequency of greater than 1 year in every 4. This will also coincide with the need for lime replenishment on acidic soils.
A base dressing, predominantly of phosphate and potash fertiliser should be applied prior to planting, and a top-dressed nitrogenous fertiliser should augment this during the growing season. The exact timing of top-dressing will vary according to the type of cauliflower being grown.

Cauliflower Groups

Early Summer Cauliflowers -These are often referred to as Alpha, Danish, or le Cerf cultivars. The crop is sown in the autumn and raised, potted, and over-wintered under protection (cold frame) prior to planting in early spring for a May - June harvest. Sometimes they may be sown under protection in a warm greenhouse during December -January for planting, after suitable hardening-off, to give a June - July crop.

Summer Cauliflowers - These belong to the same cultivar groups as above, but are sown rather later, either under glass in early spring, or later in open seedbeds to mature during July - August.
Some seed catalogues class this group together with the earlier group, and indeed certain varieties, like ‘All Year Round’, can be grown to fall within either category. The principal differences being the time of sowing and subsequent treatment.

Autumn Cauliflowers - These are mainly based on Australian cultivars, which have their own distinct curd form. They are more resistant to high temperatures during the height of summer than the other types and are usually grown to mature from September to early November.

Winter Heading Cauliflowers - These aren’t true cauliflowers but a type of heading broccoli originally widely cultivated in the Roscoff area of Brittany (the Roscoff cultivar group). In the UK they can only be grown in area of mild winter conditions, such as those found in Devon and Cornwall. They possess the typically incurving leaves of broccoli. There is also a group of cultivars originating from Holland (the Walcheren group) which are generally slightly more hardy, and more suited to less mild areas, but can still be badly affected by harsh winter conditions. Some recent introductions (hybrids) exhibit greater winter hardiness and permit cropping in less mild areas.

Winter Hardy, Spring Heading Cauliflowers - This type has become increasingly popular, particularly in the eastern counties of the country. The plants are fairly frost hardy and the crop can stand over-wintering in the open, then heads-up during early spring to mature for a March to May harvest.

Choosing the type(s) of cauliflower to grow is influenced by; whether winter protection can be given, whether there are facilities to raise early in spring under glass, whether winters are generally mild (frost free, or light frost) in the area, or whether they can withstand high summer temperatures. It is likely that one area, ideally suited to all types of cauliflower, will be very rare in the UK, so choose the type(s) that are likely to ‘do’ in your area, and forget the rest. Cauliflowers are demanding enough, without taking on extra difficulties inherent in growing unsuitable groups in unsuitable conditions. Most good seed catalogues will guide you as to the varieties within each group that are more likely to be successful in your location, so spend some time browsing them.

Unusual Varieties - These include the Romanesco types with their distinctive conically turreted green curds and standard curd types with coloured curds in lime green, purple or orange for a ‘different look’. They are usually grown from a March-May sowing for a late summer/autumn harvest. Treat them as a summer variety, though the Romanesco types will usually be autumn maturing.

Mini - Cauliflowers - suitable varieties of summer/autumn maturing cauliflowers for the production of mini-curds are usually listed in most seed catalogues. Raise and grow them as for normal cauliflowers, but their final planting distance is much reduced. A planting density of between 20 and 40 plants per square metre is not uncommon. Fungal disease may be more prevalent at this close spacing and regular checks should be made. Mini cauliflowers, owing to their closer spacing, tend to mature at the same rate and the whole of a planting can be ready for harvesting at the same time, unlike ‘normally’ spaced cauliflowers which mature with a ’staggered’ timing over a few weeks.


Raising Transplants
Nowadays, cauliflowers are rarely raised commercially by sowing in open seedbeds and transplanting. For a long time transplants have been raised by growing in compressed peat blocks, but bought-in plants grown in modules by specialist propagators are increasingly replacing even this method.
Raising cauliflowers from seed in sterile compost gives a better chance of avoiding pests & disease in the young plants and gets them off to a good start. Cauliflowers germinate readily from seed and having them at home or in your greenhouse enables their progress to be monitored more frequently and more readily than if sown in the open on your plot. Cauliflowers must be grown steadily without check and it is especially important to ensure they are not allowed to become too dry at any stage.
Most packets of seed, even the F1 hybrids, contain many more seed than you are likely to need in one year, even if you carry out multiple successional sowings, so re-seal the packet and store it somewhere cool and dry, and surplus seed will last for at least 3 years.
Seed sown thinly on the surface of multipurpose compost, then given a light covering of more compost or vermiculite, then watered, will usually ‘chit’ within 24 hours at 21 deg C. After 24 hours, place the seed tray somewhere cooler (15-18 deg C) in full light, otherwise the seedlings will become drawn and spindly. The seed leaves should emerge above soil about 3-5 days after sowing. As soon as the seedlings are large enough to handle prick them out individually into 3” pots, or the individual cells of a four/six-cell plant tray, filled with multipurpose compost.  When pricking out, place the seedling so that the seed leaves are almost touching the surface of the compost, so that when watered and the compost settles, there is no more than about 0.5 cm of stem showing. Young cauliflower seedlings are susceptible to damping off (Pythium) and downy mildew (Peronospora), especially if sown too thickly, over watered, or kept in too moist an atmosphere. In very dry weather, powdery mildew (Erysiphe) may arise. Give a preventative spray of Cheshunt Compound solution in the early stages of germination and follow this with a further spraying after pricking out. Keep the seedlings in full light but not hot sunshine until they have grown to planting out size. An occasional weak liquid feed of balanced fertiliser at fortnightly intervals after an initial 3-4 weeks will keep the plants growing steadily, particularly when grown in multipurpose compost. Give plenty of light and fresh air and keep cool. Do not over feed, as this will cause weak sappy growth. If over-wintering ‘early’ cauliflowers in a cold frame cease feeding over winter until the spring and protect from frost. Keep an eye open for any signs of downy mildew, and spray with fungicide as necessary. When using fungicides read and observe the instructions on the label.