Wasabi, according to the late food writer Shizuo Tsuji, grows best on the banks of cold, clear streams.

"In fact," he writes in his 1980 culinary treatise, "Japanese Cooking," the plant can only be grown "in flooded mountain terraces." However, thanks to the initiative of an English watercress producer, green thumbs across the U.K. can now grow wasabi in backyard flower pots, next to their geraniums and begonias.

You can thank, or blame, The Wasabi Co. for uprooting the plant from its pristine mountain terraces in Japan and making it available in the U.K.

Since 2010, the company has been growing two strains of wasabi — Green Thumb and Mazuma — at its watercress farms in Hampshire and Dorset in the south of England. As well as selling wasabi plants, the company also supplies fresh wasabi to restaurants throughout Europe and as far away as Hong Kong and Pakistan.

The idea to grow wasabi in the U.K. was first planted by a chef who visited the English watercress farms. Jon Old, general manager of The Wasabi Co., and his team were looking to diversify from watercress and use the abundant, clean spring water bubbling up from an artesian well below the farm.

"A chef visiting the farm said, 'The only thing I've seen growing like watercress is wasabi when I was in Japan.' And that's what started us off," Old tells The Japan Times.

For the first two years the project was a secret — even to this day the exact location of the wasabi farm is under wraps.

"From 2010 to 2012, we didn't want anyone knowing that we had the idea to grow wasabi, because we knew we were the only ones in Europe doing it and so we wanted to keep it that way," says Old.

They tried to make contact with growers in Japan, but it wasn't possible at first, so Old and his team learned through trial and error.

The wasabi is grown on gravel beds fed by spring water. Shade, which is essential for growing wasabi, is provided by nets and trees on the farm.

"We're growing it in a very similar way. We were always keen to mimic the Japanese cultivation methods," Old says. "Otherwise we're at the mercy of the English weather."

There have been growing pains. Early on the company lost tens of thousands of plants by not controlling the flow of water. They also had to overcome "wasabi prejudice" — initially some of the chefs making Japanese food in London were skeptical of U.K.-grown wasabi.

"I did a lot of the 'Wasabi Pepsi challenge': You put a Japanese rhizome against a Wasabi Co. rhizome and you switch them around see which one the chef prefers. Sometimes we would win, and sometimes the Japanese one would win."

But what chefs did notice is that there was a difference with Old's wasabi: it stood out for its freshness and unique taste.

These days, demand is outstripping supply; the Wasabi Co. is supplying high-end restaurants throughout Europe, as well as gardeners looking to try their hand at raising an exotic rhizome. Old also says he is planning a visit to Japan later in the year. Perhaps it will be a chance for him to try out his "Pepsi challenge" on the world's most discerning wasabi judges: Japanese chefs.