Because this is when the food calendar's spiciest event, the Chilli Fiesta, takes place. Go to Sussex this weekend and find 200 ways to make your eyes water.

An exuberant Red Hot Chilli Pepper Fiesta is an unexpected event in the leafy depths of rural Sussex.

An exuberant Red Hot Chilli Pepper Fiesta is an unexpected event in the leafy depths of rural Sussex. Yet for the last six years, British chilli-heads have descended on the restored Victorian walled kitchen-gardens of West Dean, near Chichester, to taste some of the 200 chilli varieties on display. For two days, they revel in chilli culture, with everything from chilli hats and salsa music to specialist seed catalogues and peppery sauces on display.

The British have always had a taste for spice, despite the fact that it is not commonly perceived as an intrinsic part of the national diet. Our enthusiasm for chillies took off in the 18th century with the colonising of India. Cookery books such as The Art of Cookery Made Plain and Easy by Hannah Glasse (1747) gave authentic recipes for spicy curries, as did Eliza Acton's Modern Cookery for Private Families in the following century.

More conservative diners preferred to control their chilli fix by administering it in the form of spicy sauces – which, in turn, often had an extra kick from home-made chilli or cayenne vinegar. Half an ounce of cayenne pepper to one pint of vinegar was enough to put hairs on the smoothest Victorian chest!

The current craze could, in part, be laid at the door of a young American called Dodie Miller, who was living in Notting Hill in the early 1990s. Eight years ago, she founded a mail-order company called the Cool Chile Co. She started to import dried chillies from New Mexico, including spicy, nutty-tasting, burgundy Cascabels; mild, green, toasted Pasados and Chipotles (smoked jalapeños). "I discovered that chilli-eaters divide into two groups," she says. "They either want to sit in a corner and eat the hottest chilli they can find, or they are real chilli flavour-addicts."

Soon, she was supplying restaurants, food manufacturers and Sainsbury's Special Selection range with her chillies. "Smoked jalapeños add a mild, smoky depth to the sauces in ready-made dishes," she explains, "whereas chefs are more interested in chillies that work well with fusion cooking, like the Facing Heaven Chillies from Sichuan." David Selex, for example, head chef at the Sugar Club in London, crushes roasted Sichuan chillies on langoustines that have been briefly cooked in a Japanese ponzu sauce. Miller's main problem was educating people about the diversity of the chillies available and how best to utilise them. Their flavour can be intensified by dry-roasting and most need to be soaked before they are used.

Chillies – all part of the Capsicum family – may have been eaten in Central and South America for 7,000 years, but they spread around the world like wildfire after Christopher Columbus brought home a few plants in 1492. There are two main species, C. annuum and C. frutescens. The former is an annual and can vary in heat from a mild Hungarian Paprika pepper to hot Jalapeños. C. frutescens is a perennial and usually has very pungent clumps of small, fruit-like Piquins (bird peppers).

Every chilli has a different flavour and degree of heat – hence the need to be cautious as a cook. Their heat is officially measured by Scoville heat units, which range from 0 with a Bell pepper to the ultra ultra hot 300,000 Thai chilli.

Every country that has grown chillies has developed new strains to complement its cooking. Thus lime offsets and coconut cools the intense heat of Thai chillies, just as the mild rich flavour of the Spanish Choricero chilli is wonderful stewed with beans or tomatoes. Fresh green Anaheim chillies are glorious char-grilled in Mexican chilli dishes, just as the ultra-hot but fruity habanero adds a fresh roundness to Caribbean salsas.

Matthew Simpson, part of the family business of Simpson Seeds, fell in love with chilli plants while travelling around the Balkans as a student. "I was really struck by the amazing diversity of chillies grown there. They varied from hot Cherry chillies to amazing-tasting Paprika peppers," he says. He began to collect seeds from around the world, often attracted by evocative names, like the Bulgarian Carrot chilli, which is yellowy orange and very hot, the fierce Jamaican Hot Yellow and the Thai Hot Dragon.

Sarah Wain, garden supervisor at West Dean Gardens, has also become increasingly addicted to finding new varieties. She contacts agricultural research stations in countries as far afield as America or Taiwan, who then send her a few seed samples from selected countries such as Peru, Indonesia or Korea. "Chillies are really mushrooming as a new food crop around the world, everywhere from Africa to India and Japan," she says. "They all taste different. African chillies, for example, are very small and as hot as Hades, while the Indonesian chillies tend to have a hot, clean, sharp flavour."

Her interest was initially fired by her husband, Jim Wain, West Dean's head garden manager. He visited a big chilli fiesta in South West America and decided to introduce the idea here. Their first festival was for one day and attracted 3,000 visitors. Six years on, the festival has grown in size and popularity to become one of the hottest food events of the year.

Chilli Fiesta, today and tomorrow, West Dean Gardens, Chichester, West Sussex PO18 0QZ (01243 818210 or 811301)