What is the difference between SL28 and SL34 coffee?

Developed during the 1930s at the former Scott Agricultural Laboratories in Kenya, SL28 and SL34 remain the gold standard for the country's specialty coffee industry. Both varieties were selected for their exceptional cup quality and ability to thrive in Kenya's high-altitude, volcanic soil. Despite their shared history, they are distinct cultivars with unique genetic lineages and physical traits that influence how they grow and taste.

Genetically, SL28 is classified as Bourbon-related, while SL34 is Typica-related. Visually, you can often tell them apart in the field: SL28 trees typically have green-tipped leaves, whereas SL34 trees display a distinct dark bronze color at the leaf tips. Both varieties are tall-statured plants that require careful management, as they are unfortunately highly susceptible to common coffee diseases like Coffee Berry Disease (CBD) and leaf rust.

In the cup, both varieties are celebrated for their vibrant, phosphoric acidity—a hallmark of high-quality Kenyan coffee. SL28 is frequently described as having a juicy, wine-like complexity with pronounced notes of blackcurrant, dark cherry, and sometimes savory tomato-like undertones. SL34, while sharing that signature brightness, is often noted for having a slightly heavier, more syrupy body and a profile that leans more heavily into citrus notes.

For the home brewer, these varieties represent the pinnacle of Kenyan terroir. Because they are so expressive, they perform exceptionally well in filter brewing methods that highlight clarity and acidity. However, they can be demanding; their high acidity requires precise brewing parameters to ensure the cup remains balanced rather than overly sharp. Understanding these differences helps you appreciate the nuance in your morning cup, whether you are chasing the deep berry sweetness of an SL28 or the bright, citrus-driven depth of an SL34.