URBAN gardener and TV presenter James Wong doesn’t have a greenhouse, propagators or teams of gardeners, yet through obsessive trials in his own back garden he has managed to grow a range of exotic fruit and veg worthy of any Michelin-starred restaurant.

He laments that we have become stuck in a 1940s timewarp during the ‘grow your own’ revolution, barely moving beyond spuds, sprouts and swedes.

“The biggest mistake people make is trying to grow exotic crops in greenhouses when they simply don’t need to,” he says.

Wasabi, also known as Japanese horseradish, which is used as a fiery accompaniment to popular dishes including sushi, is easier to grow than watercress, he insists.

Wasabi plants can’t stand the sunshine, but thrive in cool, wet, overcast settings, which makes them perfect for growing in this country. He says: “They like semi-aquatic settings, on the banks of bogs or shady forest areas.”

Plant out half a dozen small plants in a shady spot between early spring and early autumn, covering the area in a thick mulch of organic matter and place gravel around the plants to deter slugs and snails. Keep it in the shade in summer as they hate a lot of sun.

The edible part of wasabi is its partially buried stem, which takes up to two years to reach full size and flavour, but once you have an established clump, you will have a succession of roots for many years.

Harvest them when they reach around 10-15cm long – a third of this may be below ground – and grate them fresh at the table, because they will degrade within a few hours of being grated.

Wasabi works well in salad dressing and marinades for grilled chicken or fish, or whisked into mayonnaise.

Wong has also managed to grow cocktail kiwi, a pint-sized, fuzzfree version of the original, which he says is easier to grow than apples and pears, along with asparagus peas, dahlia yams and callaloo, a Caribbean spinach, on his urban plot. All are detailed in his latest book, James Wong’s Homegrown Revolution.