Tucked in a corner of the Lim Chu Kang wilderness are plots of unremarkable-looking plants with evocative names: Sabah snake grass, black-faced general, cat's whiskers and sky-full-of-stars.
This is Mr Chew Lai Hock's garden of medicinal herbs, which he believes can be used to treat ailments ranging from diabetes to kidney stones and even cancer. While many of these treatments are unproven by science, he is a believer.
"I am not a Chinese doctor, but I have done my research on these plants," the 61-year-old said.
"You don't have to believe me, but I have seen that they work."
Mr Chew, who has worked as a carpenter all his life, first became interested in these herbs a decade ago, when he began taking tablets marketed as an all-natural health supplement. He learnt that a key ingredient was Sabah snake grass - a tropical plant formally known as Clinacanthus nutans - and obtained some to grow on his own.
That was the start of a journey that has seen him sourcing for medicinal plants from places such as Malaysia and Taiwan to cultivate in his Lim Chu Kang garden over the past five years.
They include black-faced general, a shrub with shiny dark green leaves officially called Strobilanthes crispus, and cat's whiskers, the Chinese name of a flowering plant known as Orthosiphon aristatus.
Black-faced general is typically used to treat colon cancer, while cat's whiskers is used by some traditional Chinese medicine (TCM) practitioners to help people get rid of kidney stones.
Mr Chew grows and sells more than 10 types of medicinal plants in his small garden, which belongs to the owner of a landscaping company in the area. The man, whom he met at a temple, told Mr Chew that he could use the land rent-free because the plants he was growing would help sick people.
"When I first started out, he told me that I could have the land for free since the whole area was full of weeds anyway," Mr Chew recalled.
"Now, I just pay him $300 a year for water and electricity costs."
Although the exact health benefits of these herbs have not yet been scientifically proven, Mr Chew said that his customer base has been growing steadily over the years.
"Both old and young people are buying them, to treat illnesses and as a way of staying healthy," said Mr Chew, who earns between $1,000 and $2,000 a month by selling his produce. His bestseller is Sabah snake grass, the popularity of which can be traced back to 2008, when a Malaysian man claimed that the plant had cured his thyroid cancer.
Mr Chew sells 1kg of fresh leaves and stems for $20, or packets of assorted herbs, which can be brewed like tea, for $19.
TCM physician Gee Swee Sien, who is from Thomson Chinese Medicine, said research has shown that Sabah snake grass contains anti-tumour elements. "Though it has gained popularity in recent years, the mechanism as to how it prevents or cures cancer is still unknown. More research is needed to validate these medicinal claims."
Mr Chew, who takes the herbal concoction himself, has no such reservations. "I used to have a lot of problems but since taking this, I haven't needed to see a doctor in five years," the father of three said. "When my children fall sick, I tell them that it's there, and you can take it whenever you want."