The Arabica coffee plant originated in Ethiopia, according to the Just About Coffee website. The beans require a slow growing process to have a concentrated flavor and the plant is grows best at altitudes of 3,000 to 6,500 feet. Each plant yields between 1 and 1 1/2 lbs. of green coffee beans each year.
According to Coffee Research, the best climate for growing Arabica plants is sub-tropical with high altitudes where rainy and dry seasons are well defined. When these conditions exist, as in countries such as Mexico, Jamaica and Zimbabwe, there is one maturation season (in the coldest part of the fall) and one growing season. In equatorial regions such as Kenya, Ethiopia and Columbia, the continual rainfall produces two coffee-harvesting seasons in one year.
About 2 percent caffeine, the Robusta coffee plant has a higher yield than the Arabica and is used for lower grade coffee. The Robusta plant originates from the Congo and the plant grows at lower elevations (sea level to about 3,000 feet asl). According to Coffee Fair, Robusta beans are easier to farm and are cheaper to grow than Arabica and are mainly in mass-produced ground coffees in retail outlets.
Robusta plants can handle warmer climates than the Arabica and they are less prone to disease. Most of the world's coffee is grown in a band around the equator from 25 degrees north to 25 degrees south of the equator. Robusta plants are grown in the region closest to the equator because of their warm climate tolerance and the ability to grow at lower altitudes than Arabica beans.
According to Black as Midnight, loamy, well-draining soil is beneficial to both types of coffee plants. High humidity and at least 6 inches of rain a month are desirable conditions for growing coffee bean plants. Diffuse light and light wind are also helpful to coffee plants that are producing beans.