Following Ruiru 11, we turn to one of the most celebrated cultivars in the world of specialty coffee: SL28.
The Origins of SL28
SL28 was developed in Kenya in the 1930s by Scott Agricultural Laboratories (hence “SL”), during a period of active research into improving coffee quality and resilience.
Selected from drought-resistant Bourbon-related lines, SL28 was chosen not for yield, but for its exceptional cup profile and adaptability to Kenya’s high-altitude conditions.
Over time, it became one of the defining cultivars of Kenyan coffee, contributing significantly to the country’s global reputation for quality.
Why SL28 Matters
SL28 is widely regarded as a benchmark for cup excellence.
In the cup, it is celebrated for:
- Vibrant, wine-like acidity
- Juicy, complex fruit character
- Medium to full body
- Notes of blackcurrant, citrus, stone fruit and florals
Its clarity and intensity are distinctive, often delivering a cup that is both structured and expressive. For many coffee professionals, SL28 represents the pinnacle of what washed African coffees can achieve.
On the Farm
Despite its exceptional quality, SL28 presents challenges for producers.
It is:
- Susceptible to coffee leaf rust and coffee berry disease
- Lower yielding compared to modern hybrids
- A tall variety requiring more space and labour to manage
- Relatively drought-tolerant, which contributed to its original selection
For farmers, growing SL28 is often a decision to prioritise quality and market recognition over efficiency and resilience.
SL28’s Legacy
SL28 has become synonymous with Kenyan coffee excellence.
Its flavour profile has helped define the global perception of Kenyan coffee, bright, complex and unmistakably vibrant. It has also played a role in breeding programmes, contributing to the development of other cultivars aimed at balancing quality with disease resistance.
Even as newer hybrids emerge, SL28 remains highly sought after, a testament to its enduring appeal in the specialty market.
It stands as a reminder that while innovation is essential, some cultivars continue to set the standard.