While there are several different coffee species, two main species are cultivated today. Coffea arabica, known as Arabica coffee, accounts for 75-80 percent of the world's production. Coffea canephora, known as Robusta coffee, accounts for about 20 percent and differs from the Arabica coffees in terms of taste. While Robusta coffee beans are more robust than the Arabica plants, but produces an inferior tasting beverage with a higher caffeine content. Both the Robusta and Arabica coffee plant can grow to heights of 10 meters if not pruned, but producing countries will maintain the coffee plant at a height reasonable for easy harvesting.
Robusta coffee is grown at much lower altitudes (sea level-3000 feet) in an area 10° North and South of the equator. It is much more tolerant to warm conditions than Arabica coffee.
Arabica coffee is grown in relatively cool climates in the region between the Tropic of Cancer and Capricorn. The optimum temperature is between 15-24ºC (59-75ºF) year round. Photosynthesis is slowed above these temperatures and frost damage can occur when temperatures hover around 0ºC. Ideally, 1500-2500 mm of rain will fall over a nine month period with a three month dry season coinciding with the harvest. Areas with less rainfall can use irrigation to compensate. A period of moisture stress (rain after a dry spell) helps cause a homogenous flowering and therefore premotes a clearly defined harvesting season. Coffee producing countries with more than one wet and dry season will have more than one harvesting season.
Image and Information Source: Coffee Research