Loc Thuy Commune in ancient Hue has cultivated cajuput trees for centuries to extract oil locals believe could help them avoid colds and aches. 

The tradition started hundreds of years ago in the commune in Phu Loc District, about 50 km southeast of Hue Town, home to the Imperial Citadel, a UNESCO heritage site.

The oil is praised for its health benefits, including treating colds, headaches and skin irritations. To produce one liter of oil, 400 kilograms of cajuput tree leaves are manually picked and cooked for eight hours. 

Pham Huu Suy (R), 41, and his wife Truong Thi Phan, 38, residents of Loc Thuy Commune frequent cajuput plantations to hand-source leaves.

Many locals cultivate these trees, scientifically known as Melaleuca cajuputi, near the forest or on bare strips near their homes.

Two types of cajuput trees are grown in Thua Thien-Hue Province, one with smaller leaves (R) for oil extraction, and one with bigger leaves for wood.

A cajeput tree from which oil is extracted has a typical height of two meters. Their height remains the same possibly because leaves are cut from trees on a yearly basis.

Tran Van Chon from Loc Thuy Commune said he sells a kilogram of leaves at VND5,000 ($0.2) to oil makers. "Growing cajeput trees for oil is slower than growing the other type, but a tree can be harvested for up to 20 years, providing stable and higher long term income," the 62-year-old said.

The trees, which are excellent mosquitoes repellants, are harvested twice a year, he added.

Branches are cut and brought to an oil refinery, like that of Truong Huu Suy.

Leaves are placed inside a big pot with a capacity of 200 kilograms. Workers use stalks left over from wheat processing to seal the lid and ensure proper distillation.

After four hours, the first drops of oil surface and poured into a plastic bottle via a funnel. Workers later poke a hole in the bottle to allow excess water to leak out, leaving only the oil.

The distilled oil is placed in standardized bottles with labels for sale. The bottles vary from 30 ml upwards. Suy said ingredients needed to produce a liter of pure cajuput oil are priced between VND1.8 - 2 million ($77 - 86), excluding labor costs.

An array of shops selling the oil line National Highway 1A in Loc Thuy Commune. 

Nguyen Van Manh, chairman of Phu Loc District People’s Committee, said no scientific evidence exists that proves the oil produced here is better than others, but as local cajuput trees are cultivated at a slower pace than those in elsewhere, local oil is stronger and more fragrant.

Cajuput oil is believed to prevent colds, driving demand.

Tuyen Khoa (R), a show owner, said last Saturday alone she sold 300 bottles, or 30 liters of oil. A liter costs VND2.3 million ($99). "For the last three days, demand for cajuput oil was high. Many customers from Hanoi, Da Nang, and HCMC bought hundreds of bottles to protect themselves from viral epidemics," Manh said. 

In recent months, the government has aided oil producers with VND5 million ($214) per hectare to meet increasing demand.