SL9

The SL9 variety originated from the Scott Agricultural Laboratories in Kenya, a research institution established in 1903 that became world-renowned for its mid-20th-century breeding programs. During the 1935–1939 period, researchers at the lab conducted extensive single-tree selections to identify high-quality coffee plants. SL9 was selected from a block of trees of unknown origin at the facility. Unlike its famous siblings, SL28 and SL34, which became the backbone of the Kenyan coffee industry, SL9 was quickly sidelined by breeders.

In its original Kenyan context, SL9 was deemed commercially unviable. Historical records from the Coffee Board of Kenya indicate that the plant was a 'shy bearer,' meaning it produced low yields, and it was found to be highly susceptible to Coffee Berry Disease (CBD). Because of these agronomic shortcomings, the variety was largely discarded by the research station, leaving it to fade into obscurity with only minor mentions in historical variety trials, such as those in Malawi.

For decades, the variety was considered effectively lost until it resurfaced in the southern Peruvian Andes. In regions like Cusco’s Inkawasi valley, farmers began cultivating a high-quality coffee locally referred to as 'Inca Gesha.' Due to its striking floral and tropical fruit characteristics, many in the industry initially speculated that the plant was a relative of the famous Panamanian Gesha. However, this assumption was challenged as the coffee gained prominence in specialty markets.

Genetic testing conducted by organizations like World Coffee Research provided a surprising resolution to the mystery. Samples sent from Peruvian farms did not match the Panamanian Gesha; instead, they showed a strong genetic affinity to the obscure Kenyan SL9. While researchers have noted that the samples do not always provide an exact genetic match—likely due to decades of natural mutation, outcrossing, or environmental adaptation since the seeds were reportedly introduced to Peru in the late 1960s—the consensus identifies the plant as the long-lost SL9.

In the field, SL9 is prized by quality-focused producers for its unique sensory attributes rather than its ease of cultivation. It is characterized by a complex, structured cup profile that features articulated acidity, velvety mouthfeel, and notes of citrus, florals, and ripe tropical fruits. These qualities have allowed coffees identified as SL9 to perform exceptionally well in high-level competitions, including Peru’s Cup of Excellence, where it has secured top-tier placements.

Today, SL9 stands as a testament to the value of preserving genetic diversity, even when a variety is initially rejected by mainstream agricultural standards. While it remains uncommon in global cultivation, its resurgence in Peru has turned it into a sought-after 'hidden gem' for specialty roasters. The story of SL9 highlights the complex intersection of colonial-era agricultural research, the migration of coffee germplasm, and the modern specialty industry's ongoing quest for unique, high-quality flavor profiles.