Arabica, Varietals and Terroir

Coffea Arabica is the key species involved in the production of great coffee. The tree grows within the Tropics, at altitudes usually between 2,000 feet (800 metres) and 6,500 feet (2,000 metres). It needs a minimum of 1,300mm of rainfall a year, but also good drainage, and is very susceptible to frost. But it doesn’t like too high a temperature either (ideally between 15-24°C). Hence it’s a bit of a plant diva.

This contrasts with its more down-trodden cousin, the Coffea Canephora species, with its most renowned variety being Robusta. It can grow at lower altitudes (down to sea level) in hotter conditions (24-30°C), is much hardier and disease resistant, is more productive and contains nearly twice as much caffeine as Arabica. Unfortunately, it rarely tastes anything other than poor and unsophisticated – and that’s being kind to it. But the resulting cheaper price makes it much more palatable to the roasting industry. Around 40% of world coffee production is Robusta.

The Arabica coffee tree is usually kept more like a bush (to enable easy picking) although it can grow as high as 20 feet. It normally flowers once a year, after rains – when the delicate white blossom and amazing jasmine scent make it a must-see for coffee enthusiasts – enabling the development of the plant’s cherries. It takes around 9 months from flower to cherry. This makes most coffee crops seasonal. Arabica is primarily a self-pollinating tree, whereas Robusta relies on cross-pollination.

The coffee cherries form in clusters on the tree, ripening from green through to red (although there are some yellow and orange varieties) and often at slightly different times – this is due to both the time when the flower was pollinated and altitude as coffee ripens more slowly the higher you go.

This theoretically makes harvesting trickier as the pickers cannot take all of the tree’s ripe fruit at the same time. In reality, when pickers are paid by volume they are likely to harvest what they can, when they can. The best farms ensure that only the ripe cherries are harvested and educate their workers to do so – they may also offer financial incentives. It also means that pickers must be sent out to the same areas again to re-pick the same tree. Unsurprisingly, this makes production costs much higher which is one reason why the best coffees are priced much higher.

Within each coffee cherry there are two seeds – the green coffee beans – protected by layers of skin and sweet, sticky flesh (the pulp and mucilage). Occasionally the two beans fuse to form a single “peaberry”.

Like any good fruit, the coffee cherries – and sometimes the beans within – provide a tasty treat for insects and some other, larger animals. Insect damaged coffee is bad for both the farmer and the coffee drinker. It’s also bad for the insect, as nature’s reason for having caffeine in the cherry - and in even higher concentrations in the beans – is to act as an insecticide. It essentially messes with the bugs’ nervous systems, giving them a sizeable hangover. The theory on Robusta’s higher caffeine content is that it has to contend with more hungry insects at the lower altitudes – insects are much less of a problem at high altitude.

Arabica trees’ susceptibility to disease and insects frequently encourages the use of herbicides, fungicides and insecticides, alongside traditional cultivation methods to find the hardiest varieties (by accident or intervention). Success and productivity also relates to the use of fertilizers and more yielding varieties, and the natural mineral content of the soils (rich, volcanic soils are ideal).

The downside to this is that some of the hardier, more productive varieties have more of a tendency to produce bland, uninteresting coffees and there are the wider environmental implications of using too many man-made substances.

The ability to use chemical assistance relates to income, hence many of the smallest farmers are organic in terms of farming method (if not always certified as such). In times of low coffee prices, the ability to invest in fertilizers diminishes, which can be at the expense of the crop quality and condition of the coffee plants. On the flip-side, scores of farmers are adopting organic and sustainable methods of coffee farming which can only be a good thing (assuming they receive the deserved income premiums).

Arabica coffee cherries ripen more slowly at higher altitudes in the cooler conditions, and also develop harder, denser beans. This simple factor often means sweeter coffees with more complexity when roasted.

This means that on the same farm, the coffee cherries growing at lower altitudes will be ripe enough to pick earlier than those at the highest parts of the farm. It also means that the highest quality, most sought after coffee will frequently come from the higher areas of the farm – and that you have to wait that little bit longer for them…

Climate is also a significant factor in the cultivation of Arabica, and the success of the harvest and size of the crop all depends upon having the right conditions at the right time. The coffee trees must have adequate levels of rainfall to successfully flower, and heavy rainfall can slow the development of the ripening cherries. Rain can also affect the ability to harvest and dry the coffee if falling at the wrong time – for instance, Costa Rica’s damp climate means that artificial drum dryers have to be used at the expense of sun drying patios. More extreme weather – hurricanes being a particular example – can be devastating to an entire crop.