One of the delights of late summer is a crunchy cob of sweetcorn.

One of the delights of late summer is a crunchy cob of sweetcorn. Armed with a decent set of teeth and spurning knives and forks, you must devote all your attention to the challenge. The North American crop, maize, grown for thousands of years by native Americans, was first cultivated by European settlers in 1779, but it wasn’t until 1884 that sweetness was introduced to the plant when the Shakers produced Shaker’s Early Sweet. Thus sweetcorn, as we know it, was born.

When choosing a variety, ask whether there is a good place in the garden to grow it. Will the variety grow well in Scotland? How uniform should the crop be? How sweet do you want the cob and how will you use it in the kitchen?

Sweetcorn needs a warm, sunny, sheltered spot, with moist, free-draining soil -- the ideal garden, in fact. In some parts of Scotland, you can grow sweetcorn outdoors, preferably in blocks with plants every 20-30cm in rows 45cm apart. Baby sweetcorn is planted more closely -- 10cm between the plants in rows 20cm apart -- which makes them a good option if space is limited. You need to live in a low-lying part of the country, probably in the west, to grow outdoors. A decent summer is always welcome, but at higher altitudes and further east, good weather is vital. I have a friend, living 130 metres above sea level, who has great success with his crop in a good summer, but failed for the last two years. At 200 metres, I have no chance outdoors, and so use the polytunnel.

The second challenge for growing sweetcorn is latitude. Corn is a short-day plant and some cultivars will not flower when there is more than 13 hours of daylight, so select quick-growing varieties above slower-growing mid- or late-season ones. Fast-maturing varieties, such as Early Xtra Sweet, Butterscotch F1 and Northern Extra Sweet F1, fit the bill and the third example works well in our cooler climes. However, Sweet Nugget F1 and Conqueror F1 are slow growing and less likely to mature when the sun weakens and night temperatures drop.

There are some old-fashioned sweetcorn varieties such as Golden Bantam which aren’t F1s but are open-pollinated. This means they will naturally hybridise or cross with any neighbouring varieties, so a subsequent crop of identical cobs can’t be guaranteed. Towards the end of the 19th century, plant breeders realised maize could be easily manipulated to produce varieties with the characteristics they wanted. They then worked with maize to produce identical crops, or F1s, and the expertise was applied to every vegetable in the seed catalogue.

In 1909, the American researcher George Shull told the American Breeder’s Association how F1s could be produced. The first step was to produce a “pure line”, whereby one variety could only be pollinated by a plant of the same variety. This in-breeding process would continue for three generations. By this time the plants produced fewer viable seeds but a vigorous F1 resulted when they were crossed with another “pure line”. If this crossing or hybridisation was continued for another generation to produce F2s, these pure characteristics were lost. This explains why you can’t save your own seed from F1s and get the same characteristics. By establishing F1s in sweetcorn 100 years ago, scientists were able to develop this process, resulting in more accurate methods in plant breeding. Even now, Illinois teenagers play their part in producing F1 sweetcorn. Two varieties are grown in a field and, before pollination, students work their way through the field, removing tassels from one variety, forcing it to cross with the other and produce the desired seed. The seed from the second variety is unused.

Selecting a variety for sweetness and use is the final choice. A cob’s sweetness turns all too readily into starch, so breeders tried to overcome the problem. John Lanham introduced a “supersweet” gene to Illinois Chief in 1961, and several varieties are based on this. During the 1980s an even sweeter “sugary enhancer” was developed by the breeder AM Rhodes, and it formed the basis of many modern varieties, such as Extra Tender and Sweet F1.

As for cooking, although sweetcorn can be boiled I reckon it’s best grilled or barbecued so no flavour is lost to the water. Baby cobs such as Minor F1 are used for stir fries.

Whatever variety you choose and despite all efforts to keep the cobs sweet and fresh, I’m convinced they still taste better straight from the garden.