Sun Moon Lake Tea: How Assam Roots Became Taiwan’s Ruby Black Tea

Sun Moon Lake tea did not begin in Taiwan at all. Its bushes trace back to Assam, in northeast India, planted on Taiwanese hillsides under Japanese colonial administration nearly a century ago in a deliberate experiment to see whether a subtropical black tea variety could take to a foreign lake basin. It could, and the result is one of the more unusual agricultural stories on the island — one that Odyssey Traveller’s Taiwan Lantern Festival small group tour visits directly, on Day 9, when the group calls at a working tea farm above the lake’s western shore.

A Tea Variety from Assam Finds a Second Home

Taiwan’s tea culture is older than its black tea. Oolong and green teas had been grown across the island’s hill country for generations before Japanese colonial administrators, ruling Taiwan from 1895 to 1945, began looking for a variety suited to export-grade black tea rather than the oolongs the island was already known for. Assam’s climate — warm, humid, seasonally wet — looked close enough to conditions around Sun Moon Lake in what is now Yuchi Township, Nantou County, that colonial tea researchers imported Camellia sinensis var. assamica seedlings from India and planted them in the hills above the lake’s western shore.

The gamble worked better than anyone might have expected. The lake basin’s elevation, its persistent morning fog and its mineral-rich soil turned out to suit the broad-leafed Assam bushes almost as well as their native hills did, and Yuchi became one of the only places in Taiwan producing true black tea rather than oolong. For decades, output stayed modest and mostly local. What turned this into a story worth visiting on a tour, rather than a footnote in colonial agricultural history, happened after the Japanese left.

From Assam Cuttings to Taiwan’s Ruby 18

After the Second World War, the Taiwan Tea Research and Extension Station took over the breeding work the colonial administration had started. Researchers crossed the original Assam plantings with indigenous Taiwanese wild mountain tea, aiming for a hybrid that kept the malty depth of Assam black tea while adapting more fully to local growing conditions. The result, developed over decades of selective breeding, was registered as Taiwan Tea No. 18 — a name few visitors ever hear, because almost everyone in Taiwan simply calls it Ruby 18, or Hong Yu, for the deep red-amber colour of the brewed liquor.

Ruby 18 has since become the tea most associated with Sun Moon Lake tea as a category, distinct from the high-mountain oolongs grown elsewhere on the island. Tasting notes consistently mention cinnamon and a faint mint or camphor note in the background, alongside the fuller malt and stone-fruit character it inherited from its Assam parent — an unusual profile that tea specialists sometimes describe as tasting like nowhere else in Taiwan, because nowhere else in Taiwan grows quite this hybrid at quite this elevation. It is worth knowing before the visit, because it explains why the farm the tour visits treats a tea tasting as a small piece of local history rather than a routine souvenir stop.

What Actually Happens at the Assam Tea Farm Visit?

On Day 9, after two nights at the Lalu Resort, the group is driven a short distance to a working tea farm above the lake — the itinerary calls it the Assam Tea Factory — where the visit centres on seeing the tea bushes in their growing rows and learning how the farm processes leaf into the finished black tea. The visit is folded into the day’s included itinerary alongside the Holy Monk Shrine, dedicated to the Buddhist monk Xuanzang, whose seventh-century journey from China to India is remembered at a shrine just around the lake, and a private motorboat crossing later in the afternoon.

Will the Tea Bushes Be Picked When the Tour Visits?

No — the Taiwan Lantern Festival tour runs in February, timed to the Lantern Festival itself, which falls well outside the harvest window. Sun Moon Lake’s black tea is typically picked from June through July, when the new growth reaches the right maturity for the rolling and oxidation process that gives Ruby 18 its colour. Travellers visiting in February will see mature bushes and dormant winter growth rather than an active harvest, but the farm’s processing facilities and finished-leaf tastings run year-round regardless of picking season.

Reading the Day at Sun Moon Lake

The tea visit sits inside a day that says more about how Odyssey paces this tour than any single stop does on its own. The group arrives at Sun Moon Lake on Day 8, following a route down from Tainan’s old fortifications and imperial-era streets further south, and stays two nights at the Lalu Resort, built on the site where Chiang Kai-shek once entertained visiting dignitaries. Day 9 itself has no long coach transfer — the tea farm, the Holy Monk Shrine, Wenwu Temple and a private boat ride around the lake are all local outings from the same base, which makes it one of the more unhurried days on the route. The following morning the group continues north, eventually reaching the Taoyuan Lantern Festival before returning to Taipei — a very different kind of lantern display from the sky lanterns released earlier in the tour at Pingxi, and one covered in its own article for travellers who want the contrast in full.

How Much Walking Does the Sun Moon Lake Day Involve?

This is one of the gentler days on the itinerary. The tea farm visit is a walk through growing rows and processing areas on generally level ground, and the lake crossing is by private motorboat rather than on foot. The tour’s overall activity level is rated Level 2 – Moderate, meaning travellers should be comfortable with three to five hours of activity most days and up to eight kilometres on uneven ground, but Day 9 sits toward the easier end of that range rather than the more demanding coastal walking days earlier in the week.

Is There Time to Buy Tea to Take Home?

Yes — tea farms in the Sun Moon Lake area typically sell packaged Ruby 18 and other local teas on site, and the visit is structured with enough time to browse before the group moves on to the Holy Monk Shrine. Solo travellers on the tour will find this an easy stop to manage independently; nothing about the farm visit requires pairing up, and tea keeps well for the remainder of an eleven-day trip. Travellers wanting a broader answer on what to pack or how much luggage space to leave for purchases can find more general guidance in Odyssey’s Questions About Taiwan guide, which covers planning questions that sit outside any single day’s itinerary.

A Lake, a Lineage, and a Cup of Tea

What makes Sun Moon Lake tea worth a dedicated stop, rather than a passing mention in a lake-scenery itinerary, is the lineage behind it: Assam seedlings planted a century ago, crossed with wild Taiwanese mountain tea, and shaped by decades of research into a variety that exists nowhere else. It is a small, specific piece of agricultural and colonial history, made tangible over a cup with cinnamon and mint on the nose. Alongside the National Centre for Traditional Arts and Yilan’s landscape architecture further north on the route, it is one of several stops on this tour where a single visit opens onto a much longer story about how Taiwan’s culture has been shaped by outside influence and quietly made its own. For travellers who want the full arc — from the Pingxi sky lanterns to Sun Moon Lake and back to Taipei — the Taiwan Lantern Festival pillar guide lays out how all of these stops fit together across the eleven days.