Environment & Temperature
Arabica coffee trees prefer an environment which provides a year-round average temperature of 65 to 75 degrees Fahrenheit. The Robusta trees, however, are typically located in hotter, more humid environments, and at lower altitudes (600 to 1500 feet). Given that it only takes minutes for freezing temperatures to have a negative effect on coffee trees, frost is one of the biggest environmental threats to the cultivation of coffee.

Rainfall
Coffee trees thrive in an environment that provides at least 75 inches of rainfall per year.  The rainfall is best received when spread over a 9-month period, with a ‘dry spell’ of about 2-3 months during which only a few inches of rain are received. This dry spell is needed to promote new growth, budding and flowering. In areas that do not provide adequate rainfall, irrigation systems are employed.

Soil
Equally important is the temperature and make-up of the soil. Optimum soil temperatures will hover somewhere around 80° F and will generally be porous with a neutral pH level. Soil should not be too loose and sandy, nor should it be packed which promotes standing water. It is important that the roots of the tree are allowed to breath. Constant standing water will suffocate the roots causing the leaves to turn yellow, and will eventually kill the entire tree. When trees are planted, much care is taken to ensure proper drainage to avoid root-rot in the event of excessive rainfall.
Learn more about shade grown variety beans.

Humidity
Humidity is also a friend to the life of a coffee tree. Preferring a humidity level of about 90%, the air performs two functions: one is to keep evaporation from the plant at a minimum, the other, to diffuse the light. Humidity is microscopically small water droplets in the air. These droplets lightly disperse the light. Again, this varies with the type of coffee plant.

Sunlight and Shade
Shade is another important factor in the cultivation of coffee trees. Though many types of coffee trees are able to withstand direct sun light, partial shade is preferred to prevent the sun from baking the richness out of the soil. Certain varieties of coffee trees may also be susceptible to leaf damage from constant direct sunlight.

Arabica coffee trees grow best when their daylight time is split; half spent in essential direct sunlight and the other half, equally essential, shaded from direct sunlight  Coffee trees grown on mountain sides, receive direct sunlight during part of the day, then the mountain shades the trees for the remaining daylight hours.

For similar reasons and in areas where mountain sides are not accessible or available, coffee trees are planted among taller established trees of varying varieties (sometimes coffee trees that have been allowed to grow to their full height). Coffee harvested from trees grown in this fashion is often referred to as Shade Grown coffee.  The coffee trees are again planted in a way that provides direct sunlight during part of the day, and then the canopy of the taller trees is used to provide shade for the remainder of the daylight hours. One drawback to this sort of planting is that mature trees used to provide the canopy (as well as other forest growth) acquire their water and essential nutrients from the same source as the coffee trees. If not managed correctly shade providing trees could potentially starve the coffee trees of the necessary water and nutrients they require for maximum growth.

In more recent years, cultivation has moved from mountain sides and forests, to high altitude plains and/or land clearings. Trees are planted in a way that both maximizes space and lends to ease of harvesting. Coffee planted in this fashion is usually a variety that will withstand direct sunlight. When cultivating in this fashion, ground covering crops, mulch and/or trimmings that result from pruning the trees are often used to protect the soil from being parched.

Wind
Wind is another detrimental force of nature that coffee growers must contend with, especially with newly planted or young trees. In addition to quickly drying out the leaves of the tree, wind may also carry in unwanted grasses or weeds and crop damaging insects. In areas where coffee trees are planted at higher altitudes, there is the additional risk of winds passing over snow covered mountains bringing in a cooler wind will encourage the leaves to dry out at a faster pace.