Every now and then a coffee lands on our cupping table and makes us stop mid-slurp. The cup tells you one story. The paperwork tells you another. And somewhere between the two sits a mystery nobody has quite been able to solve.
SL9 is one of those coffees. Its name points to Kenya. Its genetics point to Ethiopia. Its address is in Peru. And the full story of how it got there may well be lost for good.
Here's what we do know.
An SL from the wrong continent
If you know your coffee varietals, the "SL" prefix probably rings a specific bell. It stands for Scott Laboratories, the agricultural research station founded in 1903 under British colonial rule in Kenya. Scott Labs is where SL28 and SL34 were born in the 1930s, and those two varieties have gone on to define the cup profile of Kenyan coffee for the best part of a century. Blackcurrant, tomato leaf, that electric acidity. If you've had a great Kenyan, you've probably had an SL.
So when our exporters in Peru, Origin Coffee Lab, first mentioned SL9 to us, the name raised an eyebrow. SL9? As in, one of the early numbers in the Scott Labs selection programme? In Peru?
The numbers tell you that SL9 must have come before SL28. And it did. According to a 1956 bulletin from the Coffee Board of Kenya, SL9 was a single-tree selection from "a block of unknown origin" at Scott Labs. It was considered a shy bearer and hopelessly susceptible to coffee berry disease, so the breeders quietly dropped it. There's a surviving record of one variety trial in Malawi, and that's about it. SL9 was supposed to have disappeared from the story.
Except, apparently, it didn't.
What Scott Labs was actually doing
To understand why SL9 is such a puzzle, it helps to know what Scott Labs was up to in the first place. Its breeders weren't creating new varieties from controlled crosses. They were selecting single trees out of existing populations, watching how they performed, and propagating the ones that thrived. Some 42 trees were tagged and studied. Fifteen made it into formal variety trials. Two of them, SL28 and SL34, became household names in coffee. The rest, including SL9, mostly faded.
The trial blocks at Scott Labs contained a wild mix of material gathered from across the coffee world. French Mission Bourbon from Yemen via Tanzania. Mokka from Puerto Rico via Java. Kents from Mysore. Blue Mountain from Jamaica. Columnaris from Java. Ethiopian selections collected by British consuls in the 1920s and 1930s. It was, in modern terms, a genetic fishing expedition.
Every SL is therefore, in effect, a chance discovery. An individual tree that caught a breeder's eye. And as Dr Christophe Montagnon of the French lab RD2 Vision has pointed out, several of those mother populations were probably already genetically distinct long before they arrived in Kenya. SL9, SL28 and SL34 may well have existed as unnamed, unrecorded trees somewhere in Yemen or Ethiopia before anyone stuck a label on them.
Which opens an interesting door.
The genetic detective work
Peruvian producers have been growing a distinctive, Gesha-like coffee for years under the local name Inca Gesha (or Gesha Inca, depending on who's writing the label). For a long time, everyone assumed it was simply Gesha. The cup profile was uncannily similar, the leaves and morphology looked about right, and the assumption stuck.
Then several buyers started asking the awkward questions. The Brooklyn-based roaster Sey Coffee sent leaf samples to RD2 Vision for DNA fingerprinting. The Peruvian producer Lucio Luque submitted samples to World Coffee Research in the United States. The British roaster Colonna had separate testing carried out in France. And the Tres Cedros farm in Cusco commissioned their own independent analysis.
The results, from multiple labs working with samples from multiple farms, landed in the same place: the trees weren't Gesha. They belonged to a group of Ethiopian legacy varieties that includes SL34, K7 and Mibirizi, and they sat "very close to, and might well be" the Scott Labs SL9 selection itself. The exact genetic fingerprint isn't in any global database, which is why most people writing about these trees use the provisional label "SL9" with an asterisk rather than "SL-09". Close cousins, possibly identical, the records needed to prove it one way or the other long since gone.
How on earth did it get to Peru?
This is where the trail goes cold, and where the coffee historian Christopher Feran has done the single most thorough piece of detective work on the subject. His 2026 essay The Lost Origins of "Inca Gesha" is the closest thing to a definitive history we have, and it's essential reading for anyone who wants the full picture. The short version is that nobody knows for certain, and several plausible theories are fighting for the same space.
Theory one: the FAO expedition. In 1964 and 1965, a team of scientists from the UN's Food and Agriculture Organization toured Ethiopia's coffee regions and collected 621 samples of seed. Some 455 of the resulting seedlings were sent to Peru's Tingo María Experimental Station. Records show that 434 had survived a year later. After that, the trail goes cold: between 1984 and 1988, Sendero Luminoso ("Shining Path") guerrillas launched three separate attacks on the station, destroying the labs, the library, and half a century of field records. Whatever was growing there, and whatever happened to it, went up in flames.
Theory two: Columnaris. Feran spotted that another variety on the Scott Labs rosters, a shy-bearing, copper-tipped, coffee-berry-disease-susceptible tree called Columnaris, shares a suspicious number of traits with SL9. Columnaris was first selected in Java in the 1880s, reached Puerto Rico, then Kenya in 1931, and by the late 1950s was being grown in small amounts in Peru. It's possible that what we're calling SL9 is actually Columnaris wearing a borrowed name.
Theory three: the Yemeni shortcut. Dr Montagnon has offered an alternative hypothesis: SL9 may already have existed as an unidentified tree in Yemen or Ethiopia long before Scott Labs tagged it, and seeds from the same source population could have travelled to Peru by a completely separate route. British planters began developing huge tracts of the Andean highlands for coffee in the 1880s after Peru signed the Grace Contract, and they were perfectly capable of bringing seed with them from East Africa or India. The trees would then have stayed latent and unnamed for a century, only to be "rediscovered" much later.
Theory four: the Cusco monastery. A more recent story traces the trees to a monastery in Cusco, from which seeds were brought back to the Inkawasi district, either as recently as 2011 or as early as 1996, depending on who's telling it. There's some speculation that a Kenyan missionary may have planted the original trees at the monastery, but no documentation has surfaced to back this up.
A plot twist from a fellow UK roaster
The "SL9 was never distributed" assumption rests on paper records, and paper records have a way of leaving things out. One recent data point from the specialty coffee world adds a wrinkle worth mentioning.
Scenery Coffee, a very lovely roaster based in Southwark, London, has shared a story about one of their founders visiting a Kenyan dry mill and bringing home a small bag of Mbuni (tree-dried cherries picked at the end of the season) as a training aid for their barista trainer. On a whim, they germinated some of the cherries. Two out of fifty made it past the cotyledon stage. They kept one tree alive, in the café, for seven years, and eventually sent a leaf sample for genetic testing. The result that came back: SL9.
One tree, one sample, not a sweeping claim. But it's at least one live data point suggesting that SL9 (or something indistinguishable from it) is still being commercially cultivated somewhere in Kenya, a century after Scott Labs supposedly shelved it. The story gets another layer every time someone runs another test.
Inca Gesha: the name the farmers gave it
Before the genetic testing, before anyone reached for the "SL9" label, Peruvian farmers had their own name for these trees. Inca Gesha. The logic was straightforward: it tasted like Gesha, it looked a bit like Gesha, and Gesha was the name everyone knew.
Genetically, it isn't Gesha. The lab work makes that clear. But there's a reasonable case that Inca Gesha is a more honest name than SL9. Whatever is growing in the Andes today didn't come from Kenya. It wasn't bred by the Scott Labs team. It grew up in the Peruvian highlands, adapted to the local environment, and became part of the livelihoods of the farmers who raise it. Calling it SL9 sort of hands the credit to someone else.
We're calling it SL9 here because that's the name on the bag we bought, and because the tie to the Scott Labs lineage is what makes the story interesting in the first place. But the Inca Gesha name has a lot going for it, and we wouldn't be surprised to see it reassert itself over time.
What it tastes like
This is the part where the mystery stops mattering and the coffee takes over.
SL9 in the cup is floral, exotic and strikingly juicy. Across the lots we've tried and the tasting notes we've seen from other roasters working with this variety, the same themes keep surfacing: jasmine, bergamot and honeysuckle on the aromatics. Tropical fruit through the middle (passionfruit, lychee, ripe peach, dragon fruit, star fruit). A tea-like clarity on the finish that wouldn't feel out of place in a great washed Ethiopian or a high-end Gesha. And a sweetness that builds as the cup cools, with an acidity people reach for the word "crystalline" to describe, even though nobody quite agrees what it means.
It's easy to see why farmers assumed it was Gesha. It's doing all the things Gesha is famous for.
Where SL9 grows in Peru
Most of the SL9 reaching international buyers so far has come from two distinct clusters in Peru, and they're a long way apart.
The heartland, and the area most closely associated with the "Gesha Inca" story, is the Inkawasi (or Incahuasi) Valley in La Convención province, in the department of Cusco, in southern Peru. Farms here sit at extreme altitudes, some as high as 2,400 metres, in mist-covered ravines on volcanic soils. The best-known names are Finca Tres Cedros (the Ibias family), Finca Nueva Esperanza (Lucio Luque, who took 2nd place in the Peru Cup of Excellence in 2019 with a 91.44 and 8th in 2022), Sol Naciente (Julio Arotaype) and Los Pinos (Armando Hurtado). Brooklyn's Sey Coffee has been instrumental in bringing these farms to international attention.
The second cluster is in the Jaén area of Cajamarca, in northern Peru, where smallholders connected through Origin Coffee Lab are beginning to produce SL9 lots. This is less well-known territory for the variety, and it's where our first SL9 comes from.
Our first SL9: Peru La Palestina Washed
Finca La Palestina belongs to the Alarcón Coronel family, three generations deep, in the San José del Alto district of Jaén, Cajamarca. The farm was founded in the 1970s as a small coffee plot, and today it's a collection of parcels operated by different members of the family, with a centralised wet mill where José and Anibal Alarcón oversee fermentation and drying. They placed in the top 20 of the 2019 Peru Cup of Excellence, and in recent years have worked with Origin Coffee Lab to renovate and replant their land, introducing Gesha and now SL9 alongside the farm's older plantings of Bourbon, Caturra and Pache.
We picked this lot the way we pick most coffees: blind, on the cupping table, on the strength of the cup alone. We flagged it for the floral lift and the fruit, and only afterwards did we ask the questions about what it actually was. The backstory came second. It always should.
Peru La Palestina SL9 Washed will be available soon, in very small quantities. If you want to taste one of the more interesting question marks in specialty coffee right now, this will be the one.
Quick Varietal Facts
Varietal: SL9 (also known as SL09, Inca Gesha, Gesha Inca, Gesha Inka)
Type: Ethiopian legacy lineage; genetically close to the Scott Labs SL9 selection, though the route to Peru is undocumented
Origin of name: Scott Agricultural Laboratories, Kabete, Kenya (1930s)
First DNA-identified in Peru: Through independent genetic testing by RD2 Vision (France), World Coffee Research (USA) and laboratories in France, commissioned by roasters and producers including Sey Coffee, Lucio Luque, Colonna and Finca Tres Cedros
Optimal Altitude: 1,700m and above; many of the flagship lots come from farms at 2,000 to 2,400m
Growth Habit: Tall, with broad leaves and copper-coloured tips on new growth
Cherry Colour: Red
Yield: Low; a shy bearer, which is partly why Scott Labs dropped it
Disease Resistance: Poor. Highly susceptible to coffee berry disease (not present in the Americas) and to coffee leaf rust
Key Growing Regions: Peru, with two main clusters – the Inkawasi Valley in La Convención, Cusco (south) and the Jaén area of Cajamarca (north)
Notable producers: Lucio Luque (Finca Nueva Esperanza), Albino Ibias (Finca Tres Cedros), Julio Arotaype (Sol Naciente), Armando Hurtado (Los Pinos), the Alarcón Coronel family (Finca La Palestina)
Typical Cup Profile: Jasmine, bergamot, honeysuckle, tropical fruit (passionfruit, lychee, peach, dragon fruit), tea-like finish, crystalline acidity, building sweetness
Further Reading
Christopher Feran – The Lost Origins of "Inca Gesha"
The single most thorough piece of research on this varietal. Feran traces the history of Peruvian coffee, the destruction of the Tingo María research station, the Scott Labs selection programme, and the genetic detective work that led to the SL9 identification. A long read, but an exceptional one.
Scenery Coffee – Peru Edwin Herrera Ocampo's SL9
The London roaster's release notes tell the story of a single tree grown from Kenyan Mbuni cherries, kept alive in their café for seven years, and later DNA-tested as SL9. A rare live data point that complicates the "never distributed" version of the story.
RD2 Vision – DNA Fingerprinting
Dr Christophe Montagnon's lab is the go-to resource for genetic verification of coffee varieties. Their work has reshaped our understanding of varieties like Pink Bourbon, Chiroso, and now Inca Gesha.
Sey Coffee
The Brooklyn roaster whose work with producers in the Inkawasi Valley helped surface the SL9 identification in the first place. Their producer profiles for Lucio Luque, Julio Arotaype and Albino Ibias are among the best available.
Sweet Maria's Coffee Library – Scott Laboratories
A concise background on the Scott Labs selection programme, its history, and the varieties that came out of it.
Interested in exploring more exceptional arabica varieties? Read our guides to Geisha, SL34, and Sudan Rume.