Corn, also known as maize (from the Spanish maíz) is one of the oldest food crops, cultivated as far back as 1250BC in the region of Oaxaca* in Southwestern Mexico. Here in the UK we're most familiar with sweetcorn (though when I was a cub, the local sweetcorn crops were referred to as maize, to distinguish it from the fields of corn, which will be confusing to any people from the USA reading this. Corn is what we call wheat. And language is supposed to make communication easier!) though there are several varieties, such as Field corn & Flint corn, which is grown for making hominy & masa (a lime treated dough that is the base of many delicious Mexican foods, from corn tortillas to tamales. Yum!)
Sweetcorn is a surprisingly easy crop to grow here in the UK. Unless you live in the south, you probably won't get the huge uniform cobs that you find in the supermarkets (that have been shipped over from Morocco), but they will have a flavour & tenderness that supermarket corn can't match (as the natural sugars in those tender little kernels start turning to starch the moment you pick them). We always grew sweetcorn when I was a cub, though there was not much variety in seeds. These days you can find a breathtaking range of sweetcorn, from the supersweet F1 hybrids to heirloom varieties in every colour from red to blue!
Sweetcorn is a tender crop, so leave off planting it until the danger of late frosts have passed. You can sow seed under cover as early as April, planting them out in June, but can sow directly into the soil as late as June, so you have just enough time to get some planted out. Or you can buy young plants from garden centres & online.
If you decide to go for supersweet varieties, don't grow any older varieties nearby, as they could cross pollinate & turn starchy.
If you want a reliable, unfussy & delicious sweetcorn, you can't go wrong with 'Double Standard', an open pollinated, non-hybridised two tone (yellow & white, pretty as anything) variety that does well in colder areas & difficult soils. Real Seed offer good quality seeds that germinate beautifully, and something I grow every year. This year I'm also growing some unusual ones - the beautifully autumnal Earth Tones & the intense Black Aztec.
You'll need a sheltered, sunny spot for planting. They're gracious plants, and not fussy about soil. I've grown delicious (but fugly looking) corn on heavy clay soil, and MaFox always managed well with her thin veneer of soil over solid chalk. Corn needs to be grown in blocks, as they are wind pollinated, (unless you're growing them for baby corn, which is basically unpollinated sweetcorn, then they need to be planted in rows) at least 4 plants deep and wide, generally between 35-45cm apart (depending on the variety). Cultivation couldn't be easier, just keep the area clear of weeds & give them a bit of water in dry weather when the cobs start to form. If you live in a breezy area like me, earth up around the base of each plant to encourage stabilising roots to form. They don't really have any pests or problems. You can also grow squashes & pumpkins between the plants, which will scramble happily around them, keeping the roots cool & suppressing the weeds.
It's ready to harvest between July & October, depending on the variety & when you planted it. They're ready to be eaten when the tassels on the end of the cobs turn brown. The simplest check is to peel back the husk & pop a corn kernel with your fingernail. If a clear liquid comes out, it's not ready, so cover it back up & wait a little longer. If a milky liquid comes out (fnarr!) it's ready to eat. If what comes out resembles toothpaste, it's gone too far. But don't worry, leave to mature & dry out on the plant, then bring in before the first frosts & store somewhere airy & dry for a few weeks and use it for making popcorn (or sowing next year if it's not a hybrid variety). When you do harvest it, eat it straight away. They can be grilled, barbequed, boiled, roasted or eaten raw. And every bite will be worth it.
*Yes, Thomasina Miers, that's Oaxaca, not Wahaca. If they've been cultivating corn & making pottery for 12,000 years, you could at least spell the bloody name right.