In Tuyen Quang province, northern Vietnam, farmers in a cool, elevated village switched to greenhouse cultivation of netted melon and grapes and are earning about 2.5 billion dong (about 14.7 million yen) a year as a family. VietnamNet reported it on 10 August 2026. The move to grow high-value fruit on mountain land that had centered on rice and maize is material for Japanese food buyers to rewrite the sourcing map of 'northern highlands = tea, medicinal plants, livestock.' To make clear who this is for, this is a case for procurement and planning staff who want to gauge the capital investment in greenhouse horticulture and the conditions for recovering it.
One household running on 3,000 ㎡ of netted melon and Ha Den grapes
The article took up Doan Cong Oanh of Vi Xuyen district, Tuyen Quang province. As a family they grow a 3,000-㎡ netted-melon greenhouse and 1,000 ㎡ of Ha Den black grapes (Ha Den = Hạ Đen, a seedless introduced variety), and together farm freshwater fish such as carp, catfish, and eel on 15 rafts over about 350 ㎡ of water surface. The melon yields about 20 tonnes over two crops a year, and the family's annual sales from aquatic products and fruit combined reach about 2.5 billion dong.
On the technical side, he builds the cultivation with scientific and technical support from a northern-mountain agriculture and forestry research institute. That an external research institute is involved in the greenhouse design and variety choice, not just individual intuition, ties to the stability of the yield.
What stands out is a composition that does not rely on fruit alone. On top of the melon greenhouse and grape trellis, raft aquaculture raises carp, catfish, and eel. Fruit concentrates sales in the seasonal harvest, but freshwater fish let him stagger the shipping timing. He divides the use of land vertically (greenhouse and water surface) and evens out the inflow of income month by month. The ingenuity of drawing cash without interruption from a small site makes up for the smallness of scale.
The background to an elevated village betting on high-value crops
In the 2025 provincial reorganization Tuyen Quang province took in the mountainous part of the former Ha Giang province, becoming a region where 46 ethnic groups live with a population of more than 1.3 million. Of these, ethnic minorities make up about 73.5%. On high-elevation land short of flatland, income is hard to grow as long as it stays with rice and maize, which have low returns per unit area. Grow high-unit-price fruit such as netted melon and grapes in a greenhouse, and cash income can be drawn from a limited area.
The same flow is not confined to one household. In Sin Lung Chu village, Dong Van district of the province, village head Ly Phai Sin added Ha Den grapes to 1 hectare of yam (sam hoai), and from 2026 also introduced chestnuts, earning more than 200 million dong (about 1.18 million yen) a year. The idea of turning the cool highland climate from a weakness into material for quality is spreading at the village level.
Mr. Oanh's greenhouse operation in numbers
| Item | Details |
|---|---|
| Netted-melon greenhouse | 3,000㎡ |
| Ha Den grapes | 1,000㎡ |
| Freshwater fish farming | 15 rafts, about 350 ㎡ of water surface |
| Melon annual yield | about 20 tonnes (two crops a year) |
| Family annual sales | about 2.5 billion dong (about 14.7 million yen) |
The exchange is converted at 1 yen ≈ 170 VND, a rough estimate as of August 2026. Sales are the original text's about 2.5 tỷ đồng converted to yen. The investment amount is not stated in the original and is not shown.
What governs greenhouse-investment recovery is unit price per unit area
What to pin down in this case is the structure of recovering the initial greenhouse investment with high-unit-price fruit. Open-field rice and maize cannot earn without widening area, but the mountains have no wide flatland. So he chose netted melon and grapes, which have a high unit price per unit area, raising the productivity of limited land. The quick turnover of 20 tonnes over two crops a year also works to recover the equipment fast.
But greenhouse horticulture does not turn a profit for just anyone. In the same northern Vietnam there is also a farmer who replaced a thin paddy with a greenhouse and localized Korean-lineage grapes by investing 1 billion dong (the Noi Bai greenhouse-grape case). The larger the investment, the greater the blow when unit price and yield collapse. In Mr. Oanh's case, the technical support of a research institute and the combination of multiple income sources—melon, grapes, and freshwater fish—make a design in which the household finances are less likely to tilt even if one crop fails. More than a single-crop greenhouse, income diversification is the safety valve for recovery.
Implications for Japan's agritourism and high-value horticulture
This case can be read across to Japanese horticulture too. The structure in which rice returns do not grow on the small farmland of hilly and mountainous areas closely resembles Japan's disadvantaged land. If you cannot earn on area, earn on unit price. Growing fruit suited to picking experiences and gifts, such as netted melon and high-sugar grapes, in a greenhouse and tying it to agritourism and furusato-nozei thank-you gifts is directly an option for Japan's hilly and mountainous areas.
Another is the point of involving an external research institute from the design stage. Mr. Oanh does not go it alone; he bases it on the technology of a mountain-agriculture research institute. In Japan too, teaming up with public experiment stations or universities to settle the variety and cultivation system before committing to capital investment raises the certainty of recovery. Already in northern Vietnam's mountains there is a case where a 7,000-㎡ greenhouse produces year-round vegetables across 11 crops a year in an environment where open-field cultivation is difficult in the rainy season (the Lai Chau mountain-greenhouse case). The combination of highland × protected horticulture is gaining reality as a turnaround strategy for disadvantaged land.
The cool elevation can also be used to differentiate from the lowlands. Highlands with large day-night temperature swings make it easy for melon and grape sugar to build. If the same variety tastes different by the producing area's elevation, a basis for pricing is born there. The condition Japan's hilly and mountainous areas have treated as 'high elevation is a disadvantage' flips into a strength the moment it switches to fruit that earns on unit price. What Vietnam's highland farmers show is the path to making that reversal hold at the single-household level.
Practical points to watch in sourcing and trading
If Japanese food buyers and planning staff track this move, here are the points to confirm.
- Supply stability: at 3,000 ㎡, the scale per household is small. Securing a consolidated volume presupposes trade with a producing area bundled at the village or research-institute level.
- The variety's provenance: the Ha Den (Hạ Đen) grape is an introduced variety, and sugar content and shelf life swing by producing area. Check the actual quality with samples before advancing talks.
- Judging the use: netted melon can be used for both gifts and processing raw material. If fresh-fruit transport cost does not work, there is the option of building it on a processing premise such as puree or dried.
- The producing area's background: Tuyen Quang province is growing horticulture as an income-raising measure for ethnic-minority areas. A producing area with a story suits gift channels and branded products.
As a precedent for larger-scale greenhouse branding, in Binh Duong province there is also a move by an 80-ha greenhouse muskmelon operation to aim at gift channels (the Binh Duong greenhouse-melon case). A small-scale producing area in the northern highlands and a large-scale branded producing area in the south differ in both the shelf they aim at and the price band.
Summary
What one household in Tuyen Quang province showed is the fact that even on high-elevation poor land, combining a greenhouse with high-unit-price fruit can generate 2.5 billion dong in cash income a year. The keys are basing it on a research institute's technology, and diversifying income sources across melon, grapes, and freshwater fish to lower recovery risk. The first step a Japanese buyer should take is to confirm the quality of such mountain producing areas with samples and to decide the outlet—fresh or processed—in advance. Build contact in the early days of a producing area's growth, and it is easier to tie it to a priority trade when volume comes together.
