The story
Kenya borders Ethiopia, where coffee comes from, yet it was one of the later countries to plant it. According to the importer Cafe Imports, the first trees were brought in by Scottish and French missionaries. The French brought a Bourbon type from the island now called Réunion, which became known as French Mission Bourbon. Under British rule coffee became a major export by the 1920s.
After independence in the 1960s, much of the land moved from large colonial plantations to Kenyan smallholders. Today most farmers look after small plots, some with as few as 150 trees, according to Cafe Imports. They carry their cherries to a nearby mill, which Kenyans call a "factory". The factory weighs each delivery, then sorts and combines the cherries into lots big enough to process and sell. Many factories belong to farmer co-operative societies. Coffee Review notes that a Kenyan coffee is often named after the factory where it was processed, even when the label says "estate". Privately owned estates still exist, but there are fewer of them than in colonial times.
Cafe Imports lists more than a dozen growing regions, including Nyeri, Kirinyaga, Embu, Murang'a, Kiambu and Mt. Elgon, and credits the rich soil around Mount Kenya for part of the country's distinctive flavour. Farms sit high, from about 1,400 metres to more than 2,000 metres.
Kenya's best-known varieties came out of local research. In the 1930s Scott Agricultural Laboratories tested dozens of trees and gave the promising ones "SL" numbers. SL28 and SL34 are the famous results. World Coffee Research says SL28 copes well with drought and has very good cup potential, but is vulnerable to the main coffee diseases. After coffee berry disease wiped out about half of Kenya's crop in 1968, the research station at Ruiru bred Ruiru 11, a compact, disease-resistant hybrid released in the mid-1980s. Batian, a tall variety from the same institute, followed in 2010.
Most Kenyan coffee is sold at a weekly auction at the Nairobi Coffee Exchange, a system that dates from the 1930s. Each co-operative or estate uses a marketing agent to put its lots up for bidding. A second route, called the "Second Window", lets farmers and buyers agree a price directly.
How it's processed
A coffee bean is the seed inside a small fruit called a cherry. Nearly all Kenyan coffee is washed: the fruit is removed before the beans are dried. Kenya's version, which Cafe Imports calls "Kenya washed", adds some extra steps. Practice varies from mill to mill.
At the factory, the cherries are pulped to strip off the skin. The beans, still coated in a sticky layer of fruit called mucilage, then sit in tanks without water for one to two days while that layer breaks down. Next they are washed through channels to clean them. For some lots, especially the top AA grade, the beans then soak under clean water for up to another day. Cafe Imports describes this extra soak as lasting anywhere from 12 to 72 hours, depending on the mill.
The wet beans are first laid out thinly in full sun for a few hours, so the papery shell around them doesn't crack, then spread more thickly on raised beds to dry for about a week to ten days.
Kenyan coffee is graded by bean size. AA is the largest screen size, AB is a step smaller, and PB means peaberry, where the cherry held a single round bean instead of two. A grade tells you size, not flavour.
The main harvest runs from about August to January, with a smaller early crop from April to July.
What it tastes like
Kenya coffee is known above all for acidity: a bright, juicy liveliness rather than a flat or bitter taste. Importers and reviewers often describe dark fruit, especially blackcurrant, along with grapefruit or lime, and sometimes a savoury note like tomato or tamarind.
Coffee Review's Kenneth Davids links that blackcurrant-like note to SL28 and related varieties, which descend from Bourbon. He describes it as both dry and juicy, sometimes closer to cedar with blackberry or black cherry, and sometimes leaning toward orange, grapefruit or red wine. Cafe Imports finds the SL varieties juicy and lively, while French Mission tends to be creamier and more citrus-led.
Regions can differ too. Cafe Imports describes Nyeri coffees as sweet and juicy with tart acidity, Embu as darker and more balanced, and Kirinyaga as more floral and delicate.
Because the acidity is strong, some tasters find Kenyan coffee less suited to espresso and prefer it brewed as filter coffee. As with any origin, the farm, the variety, the processing and the roast all shape the cup, so the tasting notes on each coffee are the best guide.