Sierra Leone

Why this origin matters

Sierra Leone produces very little coffee, and it matters to a learner for another reason. A third species, Coffea stenophylla, grows wild in its forests, was farmed and exported from the country in the nineteenth century, disappeared from farms, and was found again in 2018. In 2021 a research group reported that trained tasters, working blind, mostly took it for arabica, although it grows where the average temperature is more than six degrees Celsius higher than in arabica's native range. That is a research finding about a wild plant. Nobody farms stenophylla today, and the country's own researchers explain why.

Where coffee grows

The national research institute's 2023 review names the east of the country as the centre of coffee growing: the districts of Kenema, Kono and Kailahun. It lists smaller areas in the south, in Pujehun, Moyamba and Bo, and in the north, in Tonkolili and Koinadugu. The review gives no area or production for any district. Most growers are smallholders; the review cites the International Coffee Organization for an average small farm of four hectares.

The review describes the coffee districts as sharply seasonal: six months of rain from May to October and six dry months from November to April, with average monthly temperatures of 26 to 28 degrees Celsius in the wet months. The 2020 survey notes that most of Sierra Leone lies low. The only altitude in the documents CoffeeHQ read belongs to the wild species, not to the farms: both wild stands of stenophylla were found in forest at about 400 metres.

Species and varieties

Farmers grow robusta, Liberica and arabica, and the review says the planting material of all three is introduced: the country has never run a breeding programme of its own. The oldest material is a set of nine clones brought in by the Ministry of Agriculture in the late 1950s from Uganda, Côte d'Ivoire and Nigeria, among them A2 and G98, which the review pictures as robusta. In 2019 a development project added ten arabica varieties from Brazil's agricultural research corporation, including Catuaí and Mundo Novo lines. The review gives no share of the crop for any species or variety, and does not say where arabica is planted. Liberica is also native: a 2025 genomic study counts Sierra Leone among the five countries where it grows wild.

What the tasting panels tested, and on how much coffee

The claim that made stenophylla famous rests on two samples. One came from a collection plant on Réunion that originated in Côte d'Ivoire; the other was ten grams of seed gathered from wild trees in eastern Sierra Leone. In the first test, four panels totalling fifteen judges scored the Ivorian sample blind beside an Ethiopian arabica, a Brazilian arabica and an Indonesian robusta. Asked whether each cup was arabica, 81 per cent of the judges said yes for stenophylla, against 98 per cent for the Ethiopian coffee, 44 per cent for the Brazilian and 7 per cent for the robusta. Asked whether the same cup was a coffee new to them, a little under half also said yes: 42 per cent in the manuscript's text and 47 per cent on its chart, a difference the manuscript does not explain.

The Sierra Leonean sample was too small for that protocol. A separate panel of three judges assessed it with the Specialty Coffee Association's method, adapted for the quantity, and its leader gave a consensus score of 80.25, a quarter of a point above the association's threshold for specialty coffee. The authors point out what the sample was: seed from unselected wild plants, crudely processed. They also report that some judges recorded unpleasant characteristics, which were not statistically significant.

What this supports is narrow and worth stating exactly. Two small samples of an undomesticated plant were judged, blind, to resemble good arabica. It does not show what a farmed crop of stenophylla would be like, and the paper contains no yield trial: it says only, from older reports, that yields are likely to be lower than arabica's and robusta's. CoffeeHQ read the authors' accepted manuscript; the published article is behind a paywall, and its supplementary tables, which hold the judges' individual scores, were not read. A later study by the same group compared the chemistry of the unroasted beans; CoffeeHQ has read only its introduction.

Why nobody farms stenophylla, and what it would take

The national institute's answer is short: stenophylla is not grown commercially because its yield is low and its fruit small, which makes it inferior to the other species for a farmer. The interest is in what it tolerates. The 2021 paper puts the average annual temperature where it grows at 24.9 degrees Celsius on modelled data, against 18.7 for arabica, and says arabica cannot be grown where stenophylla is found; only robusta and Liberica can.

Turning that into a crop is a breeding task that has barely begun. The institute proposes to treat stenophylla as robusta is treated, crossing chosen parent plants and selecting among the offspring, because, like robusta, it does not readily pollinate itself. Its first step has been to develop genetic markers, and it plans to propagate cuttings of selected trees for field trials. The 2021 authors see the species equally as a parent for crosses with other coffees, and note that its drought tolerance, often asserted, has not been properly tested.

Harvest

The review gives the harvest as December to March, which falls inside the dry season. Farms are weeded twice in the growing year, before flowering and again as the fruit ripens, and the trees are pruned straight after picking, with old growth cut out and four stems left to each stump. It describes the pickers as mostly the young and the old, and names a shortage of labour and of tools as the two main constraints on the crop.

How the coffee is processed

The one method the review describes is drying the whole cherry. In communities reached by a robusta development project the fruit is dried on raised platforms; elsewhere it is spread on a drying floor fenced with mesh to keep animals off. The review does not mention washing stations or any other method, and says nothing of how the dried coffee is hulled, graded or sold.

How coffee is drunk in Sierra Leone

The International Coffee Organization put Sierra Leone's own consumption at 300 tonnes in crop year 2013/14, a little over 50 grams a head. A 2020 review of the historical record notes that the small export figures for stenophylla coffee a century ago left out what was drunk in the country, which it says may have been substantial. Nothing CoffeeHQ read describes how coffee is drunk there today.

One dated estimate and one historian's caution. The per-head figure is the document's own, 0.056 kilograms.

History

Stenophylla came first. The 2020 review of the record traces knowledge of it to the 1790s, its scientific description to 1834, and its seed leaving the country from the 1850s under the name highland coffee of Sierra Leone. A trade history of 1922 records exports of all coffee falling from 33,376 pounds in 1903 to 8,228 in 1917. Commercial robusta growing dates, on the national institute's account, from the 1950s, when the first clones were imported to build an industry. By the same account the sector was built up between 1960 and 1980, most farms were abandoned after war broke out in 1991, and output has never returned to its earlier level although the fighting ended in the early 2000s. The institute adds that the surviving plantations are now too old to yield well, and that a European Union project begun in 2018 has pruned ageing trees and supplied fertiliser to bring abandoned farms back.

Highland coffee: a species farmed here, then lost

Stenophylla is a different species from arabica, robusta and Liberica: a narrow-leaved forest shrub with black fruit, native only to Guinea, Sierra Leone and Côte d'Ivoire. The 2020 review found that it was being grown in quantity in Sierra Leone in the 1890s, that seed sent to Kew in 1894 went on to India, Ceylon, Trinidad and Java, and that it remained a visible part of the country's farming until at least the 1920s. Exports were never large. The review quotes an author of 1929 for three to five tons a year from Sierra Leone and Guinea together.

It then faded. The review suggests a fall in coffee prices; the 2021 paper adds the low yield reported at the time and the rise of robusta, which was becoming a world commodity in the same years. The 1922 trade history, written as this was happening, calls stenophylla a native growth that was not a trade factor, and says its drawback was the long wait before a planting bore a worthwhile crop.

By the time anyone looked again it had gone from farms altogether. The last wild collection in the country's herbarium record dates from 1954 and the last from a farm from 1963, and the review reports, at second hand, that the last known plantation, in the grounds of Njala University, was cut down after being abandoned in the 1980s.

The search that found one plant, then a small stand

The search began on farms. Between 2014 and 2016 the survey team asked organisations representing about 10,000 coffee farmers in Kenema, Kailahun and Kono for samples of anything unusual, and sent posters showing the leaf to district agriculture offices. Twenty samples came back. Most were ordinary robusta and Liberica; three cultivated plants that had been labelled as arabica and as affinis coffee turned out, on their DNA, to be hybrids of stenophylla and Liberica. Five farms that reported growing stenophylla were visited in December 2018 and had only robusta.

The forest was the last resort. On the same trip the team found a single immature plant in the Kasewe Hills, where the species had last been collected in 1954, and then a small population, with trees up to seven metres tall growing wild, in the Kambui Hills near Kenema. Return visits in 2019 found a second species there, Coffea affinis, never before recorded wild in Sierra Leone. The paper describes both stenophylla sites as extremely localised and threatened. Its own account puts the find in December 2018; the same group's 2021 paper dates the rediscovery to 2019, the year of the return visits.

The national institute has since sequenced plants from three wild populations and from its own collection. Its 2024 study reports that the populations are genetically distinct from one another and show the signature of a recent collapse in numbers, on top of a much older decline that it dates to the last ice age. Stenophylla is listed as Vulnerable on the Red List.

Twenty thousand tons, or under ten: two accounts of the peak

The two kinds of source disagree about how large Sierra Leone's crop ever was, and CoffeeHQ cannot settle it. The national institute's papers say production reached 20,000 tons a year between 1960 and 1980. The International Coffee Organization's averages are 135,000 bags a year for the 1970s and 163,000 for the 1980s, which is roughly 8,100 and 9,800 tonnes.

They agree about the direction afterwards. The organisation's average for the 1990s is 47,000 bags and for the 2000s 53,000, with an estimate of 70,000 for 2013/14. The institute's 2024 paper gives 2,580 tons for 2022, from a source CoffeeHQ could not identify. Sierra Leone has no row in either dataset CoffeeHQ uses for present-day production, so no current figure is given here.

Pressures on the sector

• Rain at the end of the harvest. The national research institute's review says erratic rain at the end of March means cherries picked then often fail to dry to the 10 to 12 per cent moisture that export requires.
• Forest loss, for the wild species. A 2024 genetic study cites a loss of 36 per cent of the country's forest between 2002 and 2023, and the 2020 survey found stenophylla only in two forest reserves, both under pressure from logging, clearing and, in one, small-scale gold mining.
• Old trees. The national institute says the plantations that survived the war can no longer reach their potential.
• Labour and tools, which the institute names as the two main constraints, with young people leaving for the towns.
• No breeding programme: every variety farmers plant was introduced from abroad.
• Drying. Rain at the end of the harvest leaves late-picked coffee too wet for export.
• For the wild species, a habitat reduced to a few forest reserves under pressure from logging, clearing and mining.

The forest-loss figure is the 2024 paper's citation of a third party, not its own measurement. No climate projection for Sierra Leone's coffee was read.

Institutions worth knowing

• Sierra Leone Agricultural Research Institute (SLARI) — holds the national coffee collection at Pendembu in Kailahun District, and its staff wrote two of the documents this entry rests on
• Njala University — the 2020 survey reports that the last known stenophylla plantation stood in its grounds

Explore Sierra Leone's coffee from here

A reading order, not a list of everything related: each step picks up something this page raised and takes it further.

1. Step 1RobustaOne of the two species the 2020 survey found on Sierra Leone's farms, and the one that displaced stenophylla a century ago.
2. Step 2LibericaNative here as well as farmed, and the other parent of the hybrids found in the national collection.
3. Step 3ArabicaThe coffee stenophylla was mistaken for by tasters, and the reason its heat tolerance attracts attention.
4. Step 4Natural processingDrying the whole cherry, which is the only method the national review describes.
5. Step 5Robusta cultivarsWhat clones are and how robusta is bred, which is the model proposed for stenophylla.
6. Step 6UgandaOne of the three countries Sierra Leone's robusta clones came from, and a robusta origin on a far larger scale.
7. Step 7Tasting LabHow a blind comparison is set up, which is what the stenophylla panels did.