It was eaten by Mexican and central American cultures as early as 3,400 B.C. and fuelled the Aztec Empire as well as the Mayan and the Inca civilizations.
It is widely thought that the Spanish brought maize back to Europe in the fifteenth century from where it then spread to east Asia and Africa. However this view does not go unchallenged and there is some evidence in support of an alternate theory (with far-reaching consequences for historians) that maize actually spread west from the Americas to Asia before its spread eastwards from Europe.
Sweetcorn gathered popularity in the UK after World War II and is now grown extensively across southern England.
Sweetcorn, a grass, is a form of the cereal crop maize (Zea mays), harvested at a young age while the kernels are tender and sweet. A corn ear is an inflorescence (cluster of flowers around a stem) and the kernels are the fruit of the plant (more specifically a grain).
Originally a native of sub-tropical areas, sweet corn is the only vegetable which grows in darkness.
Sweet corn freshly picked from the garden is far tastier than those from shops. The reason is that the sugar in sweet corn quickly turns to starch giving a very dull flavour after only a day or so. Freshly picked sweet corn is also very nutritious, each cob giving roughly 22% of the daily requirement for Vitamins A and C, Magnesium and Iron.
A little care and planning in the early stages will go a long way to ensure that tasty sweet corn can be grown successfully in many areas.

Warming the soil
At this time of year, cold, wet soil can prove fatal to early sowings made outside. By covering prepared beds with cloches you will warm up the soil, protect it from hard frost and keep the rain off. Leave the cloches in place for a couple of weeks, then rake the soil surface before sowing seed or planting out young seedlings. Finally, put the cloches back over them to give your young plants a speedy start.
Sweet corn will only grow from seed at soil temperatures above 10C (50F), but they stand their best chance at over 16C (60F).
Sweetcorn likes free-draining, moisture retentive soil. If you can, prepare the bed the previous autumn before planting, adding plenty of well-rotted manure to the soil. Don't worry if you never had time, beds can still be made in the spring. First remove weeds and dig over the site with a spade, removing any particularly large stones. Level roughly and then work over the area with a rake to leave a fine finish.
In April, sow two seeds (2.5cm deep) in 7.5cm pots filled with multi-purpose compost. Label, water and put on a windowsill.
Remove the weakest seedling when it's about 2cm tall.
A few weeks before planting put plants in a shady place outdoors to acclimatise.
Prepare the planting site by removing weeds, digging and raking to leave a fine finish. Spread a general granular fertiliser over the site a few weeks before sowing or planting out.
Using a trowel, put plants 35cm apart with 60cm between rows.
Water well and keep site weed free.
Sweet corn should be planted in blocks to assist in pollination, and reduce the amount of wind damage.
Sweet corn may seem a waste of time in small gardens, but they are ideal for under-cropping (growing other plants between them) because their foliage lets lots of light through. Examples of vegetables which will do well with sweet corn are dwarf French beans, radish, lettuce - in fact most small vegetables.
Sweet corn are very easy to look after once they have germinated successfully. They appreciate a good watering especially when they are in flower. They also appreciate being fed at fortnightly intervals with fertilisers designed for tomatoes (i.e. not too high in nitrogen, but high in potassium).
If the plants are at all exposed to wind, it helps greatly to pile up earth around the base of the stems - this will encourage more supporting roots to grow just below ground level.

Harvesting
The sweet corn can be tested for ripeness by pressing a kernel with your fingernail - if they are ripe, this will show a creamy coloured liquid from inside the kernel. If the liquid is watery, the sweet corn needs more time to ripen; if the liquid is almost like dough, the sweet corn is over-ripe. Start this testing when the silks (long silky threads which grow out of the cobs) turn brown and start to shrivel.
Cook sweet corn as soon as possible after picking to keep that sweet taste.

Pests and Diseases
Sweet corn are remarkably free from pests and diseases, and you are unlikely to have any problems in this area. The most likely disease is 'Smut', though in the cooler climates it is rare. Smut is a fungal disease, identified by green or white growths on any part of the plant. There is no cure.

Varieties

Older varieties
These 'open-pollinating' varieties produce heavy crops, but they are not as reliable in our climate as the modern F1 hybrid varieties which have been specially bred for our northern conditions.
Golden Bantam: The only example of an older variety which you are likely to find. It keeps its place because it is reasonably early, sweet and with a good reputation for hardiness.
These varieties have made it possible to grow sweet corn outside the favoured mild areas required by many of the older varieties. There are early-, midseason- and late-maturing types – the late-maturing are taller and the cobs are often larger than early-maturing varieties, but always choose an early-maturing type if conditions are less than ideal.
John Innes Hybrid: First choice for many gardeners – early, reliable and vigorous with medium-sized cobs.
Early Xtra Sweet: A little later than John Innes Hybrid, First of All, Earliking, etc, but very popular because the grains have at least twice as much sugar as standard varieties. The cobs are large but there is a precaution – do not grow near any other variety as cross pollination spoils the flavour.
First of All: One of the very early ones – highly recommended for table and exhibition, especially in areas north of the Midlands. The medium-sized cobs are about 6in (15cm) long.
Earliking: Medium height with large cobs. An early variety with a good reputation for sweetness – a popular choice, especially in northern areas.
Early Arctic: A new one, claimed by the suppliers to crop 7 days before Earliking.
North Star: The cobs are large, and most experts recommend this one for maximum reliability in northern districts and in cold and wet summers.
Polar Vee: Another variety which is recommended for northern growers. Alternatively you can choose Northern Belle for the less-favoured areas.
Kandy Kob: Like Early Xtra Sweet, an early variety with an abnormally high sugar content.
Tokay Sugar: An odd one – as early and almost as sweet as Early Xtra Sweet but the kernels are pure white.
Kelvedon Sweetheart: A new variety which is claimed to be an improvement on Earliking.
Kelvedon Glory: The most popular of the midseason varieties. A heavy cropper, producing well-filled 7-8in (17-20cm) the kernels are pale yellow. Recommended for its flavour.
Sundance: A midseason variety which is claimed to be an improvement on the better-known Kelvedon Glory.