SL34 came out of the same 1930s Kenyan selection programme as SL28, from Typica rather than Bourbon lineage.
What it was selected for
Rain tolerance. Where SL28 was chosen to survive drought, SL34 performs in high-rainfall areas — which between them covers most of Kenya’s growing conditions.
The profile
Rich and full, with the blackcurrant character less pronounced than in SL28 and more chocolate and body in its place. Slightly less acidic and generally described as rounder.
Neither is better; they contribute different things.
Why they are grown together
Most Kenyan farms plant both, and most Kenyan lots contain both. The combination gives farms resilience against both drought and heavy rain, and it produces the balance the country is known for.
A bag specifying “SL28 and SL34” is telling you it is traditional Kenyan planting rather than the newer resistant varieties.
The rust problem
Like SL28, SL34 is highly susceptible to leaf rust and coffee berry disease, which is why Ruiru 11 and Batian were bred to replace them.
Brewing it
Filter, light roast. Its extra body forgives more than SL28 does.