Cauliflower

• Cauliflowers are a great standby crop and one of the gardener’s key favourites. They produce white curds throughout most of the year but are a challenge in hot summers.
• They are a great source of iron, manganese and folic acid as well as vitamins like C, B1 and K.

Introduction To Cauliflower Growing

Cauliflowers (Brassica oleracea Botrytis) have gone through a renaissance recently.  If you imagine in your mind, over boiled curds (the flower head of the cauli), then think again.

Cauliflower is increasingly popular, raw in salads and for dipping, as a healthy alternative to rice and as a puree. Most of us have eaten it, gently steamed or lightly boiled and covered in the delicious cheesy sauce.  It’s a wonderful melt in the mouth delight.  

Cauliflowers can be a challenge to grow well of course. It’s about choosing the right varieties and of course looking after the plants. We reckon it is possible to have them all year round and only January to mid-February is the biggest challenge of their growing season. Just bear in mind that cabbages, brussels sprouts and broccoli are more hardy than cauliflowers.

Very hot summers can be a real issue in producing fine heads. For growers in the south of the United Kingdom and throughout much of mid- to southern Europe the cauliflower is increasingly difficult to grow correctly because of the increasingly hotter summers. Heat and dry conditions produce bolting where there is premature flowering and with it scorched, brown discoloured curds. In this case if you want decent curds then choose winter and autumn varieties and not summer types.

However, their versatility in the kitchen and the fact that they are very good for you makes them well worth the effort.

They are most nutritious just lightly steamed or served raw. They are also packed with nutrients and vitamins, and offers loads of valuable dietary fiber yet is very low in fat. As well as being striking with orange, yellow or purple curds, the various coloured types all have something to offer, in the form of additional cancer fighting antioxidants. They certainly add interest on the plate.

What Is A Cauliflower?

The cauliflower is a member of the cabbage family which are the brassicas. They contain broccoli, calabrese, brussel sprouts, mustards and other cabbages. The winter caulis are a form of heading broccoli. Unlike sprouting broccoli or summer calabrese, cauliflowers form one, large, tight flowerhead known as the curd.

Soil Preparation

If you want to grow exceptional cauliflowers then get the soil right. They love a deep, humus-rich soil with a slightly acidic pH of between 6.5 and 7.5. Add lime to bring the pH up to the right alkalinity but give it six weeks at least before adding any fertilizer. Lime helps with feeding but more importantly reducing the appearance of dreaded clubroot disease. All brassicas are prone to this disease!

The ground needs to be firm before planting to encourage the growth of high quality curds. Choose a sunny spot.

With winter and spring cropping varieties which need to grow through the coldest months, choose a sheltered spot and not one with frost. A typical frost pocket is one at the bottom of a slope , where cold air collects in the winter.

When setting out the vegetable plot it might help to have shade from nearby crops like sweetcorn, runner beans and other tall vegetables.

Ensure good drainage for caulis. This is essential for winter and spring varieties. Improve heavy soils by digging to break up any hard layers persisting in the soil. If necessary add hard grit and even stones to create a drained soil. Many use raised beds as this is easier. Always allow the soil to settle for as long as possible. Avoid treading on it too much but keep it firm by some light walking.

The cauliflower loves being fed right from the start. Add 2oz/sq. yard of general fertilizer such as Growmore™, chicken or sheep manure pellets, even plenty of well rotted manure and rake in gently about a week prior to sowing or planting. 

Whilst we mentioned liming to improve soil pH, adding organic matter after that six week period helps soil hold on to nutrients and especially moisture in the summer. Some people advise two weeks beforehand – it doesn’t make a great deal of differences as long as some nutrient is available for growing.

Sowing

(a) Outdoor Sowings

Traditionally, seed sowing is done in the open ground in short rows and then transplanted later on. Check the timings on the packet but it will be later than an indoor sowing – usually March is a good starting time in the year for the outdoor types. 

Early sowings, say in January to March are made in pots or cell trays to give the plants the best of starts when they are kept outdoors (see the instructions for indoor sowing on how to best do this). It is also a good idea if flea beetle is an issue or where slugs and snails tend to roam.

We may say this many times. From the start of sowing, cover any plants that germinate outdoors with fine mesh nets to stop birds making mincemeat of the leaves. An insect mesh stabilised over metal hoops is ideal as are cloches or keeping in a cold frame. 

For sowing outdoors direct, sow thinly in a well-prepared soil. That soil needs to be raked to a fine tilth where it is crumbly. We firm it down then produce a single short row about 13mm or 1/2in. apart. Water the base of the drill prior to sowing.

Sow seeds about 15mm (½in.) deep and cover with soil.

If needs be the newly formed seedlings may need an initial transplanting to allow them space to grow. This is usually about an inch apart. Allow to grow until they form their first 2 or 3 true leaves (not seed leaves) or are between 10 and 15cm (4-6in.) tall.

In some cases we have transplanted to their final positions even before we have reached that stage just described. With our outdoor sowings, we have sometimes thinned to 7-10cm apart if that is the approach taken with April to June sowings and then don our final transplant. It all depends on the amount of effort you want to put in to grow the best plants. 

Water during dry spells and remove any weeds that appear as the young seedlings develop.  

(b) Indoor Sowings

Sow seeds in trays or modules under glass at 13°C (55F) from January through to May. Two seeds per module is best in any good multi-purpose compost. Place on a windowsill, in the greenhouse and ideally in a heated propagator. Take care not to allow the compost to dry out. Thin to the largest seedling when large enough to handle and transplant.

I sometimes also plant into trays 5cm apart or into single cell modules with one seedling per cell, to move them on further if the weather is too cold for outdoor planting. 

Once greenhouse seedlings are showing, prick them out by their first pair of leaves into trays and keep indoors.

 Again – keep the watering going throughout!

Growing On

Once the plants reach 10cm -15cm (4-6in.) tall whether indoors or not, transplant to their final growing positions. You should also transplant if needed when two or even three true leaves appear rather than just their seed leaves.

We dig individual holes for any plants with a large dibber of even a small garden spade. Keep the ground as firm as possible so do not unnecessarily disturb the ground.

There is a case for autumn sowing where they are overwintered in a cold frame and then planted out in March for the very first cut of the season in June.

Any of these grown inside will need to be hardened off by moving the plants outside during the day and bringing them back inside at night. The alternative is moving them to a cold frame to accustom them to outdoor temperatures. Acclimatisation is only needed for plants being transplanted before mid-May or June when growing in the far north.

Also water them the night before they go into their final positions. Lift any plants for transplanting carefully with a trowel or small fork. Take as much soil as possible along with any roots. Replant straight away in the prepared bed. Bury the stem down as far as the seed leaves.

Try to get 60cm or 2ft. between all plants (indoor or outdoor sowing) in the end including the rows for the summer and autumn varieties. If pushed for space, 45cm apart is the minimum but get 60cm between the rows.  Try placing plants about 2ft. 6in apart (75cm) for the winter types as these tend to be larger plants.

Some of the mini and compact varieties such as ‘Igloo‘ are better for raised beds. For outdoor planting of whatever nature allow 15cm – 23cm (5 – 9in.) apart and between rows and 10cm (4in.) between plants.

Always keep the caulis watered – another repeat message but so well worth making!

To make the most of space, grow salad crops between the rows – radish, lettuce and salad leaves are all good examples. We’ve also tried onions and garlic to really mix things up.

Pests & Issues 

Pests are a real problem for any brassicas. Cauliflowers are no exception so be sure to use protective netting throughout the life of the plant to deter flying pests like birds, pigeons in particular and cabbage white butterflies. The nets should be tight and held well above the leaves of your crop. Do this in the early stages and remain observant and vigilant of snails, slugs and caterpillars.

Nasturtiums are grown near cauliflowers to deter cabbage white butterflies which have a nasty habit of eating through all Brassica crops. Mint is grown nearby to deflect annoying flea beetles.

Keep slugs at bay by scattering slug pellets are train a hedgehog to feed around the vegetable patch. Other forms of slug control are available but I dislike the beer in a glass method as it is a waste of good beer. 

Trample the soil around the plants to keep the soil firm. Add fertiliser to the bed as you firm it down. Some people use the palm of their hand but this is too soft in many cases to get a good firmness. In areas where cabbage root fly is a problem, place a collar around the base of the stem. Cabbage collars are obtained from all good garden centres or online.

Cultivation Care: Keeping Your Cauliflowers Happy

• Cauliflowers need regular watering and hoeing to keep the weed population down and allow insect larvae to appear on the surface.

Regular watering in the early phases of growth is key. Watering also ensures the curds are not ruined by drought or stops growth checks which produces bolting. It’s also important to make sure the soil is thoroughly soaked each time rather than just giving a little sprinkle.

Generally feed with general purpose fertiliser when the plants start growing away. When plants appear slow, sluggish or undernourished with yellowing leaves, then feed with a liquid fertiliser containing a high-nitrogen fertiliser such as Miracle-Gro™ especially ammonium sulphate or similar to boost growth. Also look out for organic versions too – they work really well. Do this application when the curds start forming.

The winter types like a feed of blood, fish and bone meal in late summer. Apply this at a rate of 56g per sq m (2oz per sq yd).

Weeds are kept down by hoeing as these will harbour pests and diseases besides competing for water and various nutrients especially during the summer months.

Too much sun, rain and frost causes scorching, turning the white curds to a pale yellow and then developing brown spots. The modern varieties have now been developed to produce guard leaves which cover the curd as it develops and matures. Some gardeners actually bend the ‘guard’ leaves surrounding the curd over to protect it in especially hot weather. Repeat the process for winter crops if they are exposed to frost and snow.

Harvesting Cauliflowers

The curds are harvested when they appear large enough and when the heads are still compact and before the florets begin to lift. The modern F1 varieties tend to mature at the same time and are at their best when the florets just begin to separate. Any later and the curd is spoilt. You can cut these compact whole curds up into separate curds or slice them to form a type of steak slice.

The mini varieties are left intact. Blanch and freeze any if they cannot be eaten there and then because gluts will often occur. Cauli florets can be frozen by first blanching them with a little added lemon juice added to stop browning, and then plunging them in ice water before storing them in freezer bags. This is the best method for long-term preservation.

They can also be stored in the fridge when wrapped in a food bag or cling film and keep well for a week or so.

One other storage method is to take the autumn and winter types, lift intact and hang upside down. Store in a cool dark place or in nets.

Timings For Harvesting Based On Sowing Times And Variety

Remember, the curds can be harvested throughout most of the year with the great choice of varieties.  If overwintering your plants is not possible, sow seeds in January for cutting in June & July.

The summer cropping types include ‘Boris F1′ which can be sown in March to April for harvesting from August to September. These types can be sown even earlier – January and February if a polytunnel/greenhouse is available and heat is given. Cropping can then occur as early as June/July.

The Autumn types which follow on from varieties such as ‘White Step F1′ are then sown from April to early June for planting out in June and harvesting from September through to early December. These types are sown outside in nursery rows or in cell trays and pots.

Sowings made for the hardy winter and spring types include ‘Aalsmeer F1′. The sowings are made from April to early June for cutting from December to the following May/June the following year. The cutting time at this time of year depends on the variety. In the cold or exposed areas it is better to rely on sprouting broccoli for a winter harvest.

Not all varieties are fully hardy and even the winter types are damaged by severe weather. Seed suppliers have made the choice easier by offering seed collections to allow for an all-year crop.

Buy any plants from a garden centre to fill in any gaps!

Varieties To Try:-

Cauliflower ‘All The Year Round’ :As its name suggests, this one has a long harvesting period and can be sown in succession from January to June with harvesting from June to November. Sowing from September or October means cropping the following year from February and well into Spring. A tried and trusted variety and certainly one of the most popular. Produces compact plants with medium-sized heads. 

Cauliflower ‘Boris’ F1: A good, white-curded summer and autumn maturing type. It is tolerant of a range of soils and poor weather conditions. Great for beginners. Buy from T&M and Kings Seeds.

Cauliflower ‘Cendis’ : a good compact F1 variety with a very uniform, pure white curds. easy to harvest, with nice round frame and is suitable for high density planting. Ideal for late autumn and early winter.  

Cauliflower ‘Clapton’ F1: A variety which is the first commercially available with clubroot resistance. Has a very erect habit and well wrapped curd. Ideal for anyone who has had clubroot in the past. Produces white, medium-sized heads. A typical summer and autumn cauli. 

Cauliflower ‘Freedom”: A CMS version of the popular variety, F1 Fremont. It is considered one of the best varieties currently available for UK growing and is suitable for all work including standard growing.

Cauliflower ‘Galleon‘: A winter cropping variety with better weather resistance than many. Has an AGM from the RHS. Seeds available from Suttons. 

Cauliflower ‘Graffiti’ F1: is a stunning purple coloured cauliflower which makes it very attractive and is a great improvement on the older purple types. The colour intensifies with exposure to light. A good source of anthocyanins which are powerful antioxidants.

Cauliflower ‘Igloo‘: A very compact variety with mini heads. Excellent for smaller plots and raised beds where it can be given close spacings (30 x 30cm/12x12in.). Seeds from Kings Seeds.

Cauliflower ‘Maybach’ : An early, vigorous variety, producing high quality curds with good white colour and resistance to pinking. It has a medium to large frame which is best grown on moisture retentive soil.

Cauliflower ‘Moby Dick‘ F1. Nice dense white curds which are crisp and sweet. The plants stand up well to take Seed available from Mr Fothergills. 

Cauliflower ‘Optimist’ :A hybrid autumn type which is huge and gigantic. It is hardy with good disease resistance and performs well even in cold, wet conditions. It produces high quality, dense packed curds.

 Cauliflower ‘Redoubtable’ : Suited to production throughout the UK. It produces good uniform heads which are larger than most other Roscoff types. It is very vigorous with good habit and has a good upright habit. 

Cauliflower ‘Sunset’ is one of the first CMS orange varieties to become available. It performs best when grown for September and October harvesting.

The orange colour is most pronounced when used for ‘baby heads, but the colour is still vibrant in full size heads. The plants have a small compact frame.

Cauliflower ‘Zaragoza‘ F1 is a new high quality late summer to early autumn cropping variety with good club root resistance. The plant stands upright and has such large leaves thay are used to protect the curds. May have the best flavour of all. Sow February to May indoors for an August to October harvest, and May/June outdoors (DT Brown, Mr. Fothergills).

Romanesco Types

Romanesco: ‘Navona’ F1: Navona is a romanesco cauliflowers producing a uniform crop of dark green, turreted curds with no bracts. It is a vigorous variety with good field holding properties and comes well recommended.

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