On Aug 26, the 22nd international book fair was held in Beijing, where a big coloring wall like the Secret Garden attracted visitors. [Photo by Mai Tian / For China Daily]

A coloring book for grown-ups, Secret Garden, by Scottish illustrator Johanna Basford has sold more than 1 million copies in China since in June, becoming the bestseller with the fewest words - only 264 Chinese characters - according to Hinabook, its first Chinese publisher.

Describing herself as "an illustrator and ink evangelist who prefers pens and pencils to pixels", Basford said in an interview with NPR early this year: "I think there's something quite charming and nostalgic about coloring in."

Many of her Chinese readers describe her book as "a pressure-reducing valve" that helps people "recover from depression".

"There is something mysterious about coloring in that lets me slow down from the fast life and forget about some daily routines," says Li Yaming, a 34-year-old middle school teacher in Guangzhou, Guangdong province.

"Every reader is actually a 'co-author' of the book, or a gardener, when we participate in the 'gardening' process with Basford. In the participative reading, I feel I walk into a secret garden, and I become its owner when the whole coloring in is complete," Li says.

"The graphic patterns of plants and animals put me into nature, awaken my childhood memories, and intrigue my passion to explore the beauty of the world," says Wen Wen, a real-estate sales agent in Harbin, Heilongjiang province. Characterizing her life as stressful, the 30-year-old Wen adds: "That's why Secret Garden is more than a book to me. I am simply addicted to it. Coloring in is a creative process that concentrates my spirit and calms my nerves."