In the recent article Coffee in a Post-Collapse Society, the author is talking about Arabica coffee being only cultivated near the equator. Robusto green coffee can be grown in the southern states like Florida, south Texas (same latitude as Cuba, a coffee producing country) basically any place that citrus can grow, Robusto coffee can grow. Robusto coffee can grow at low altitudes although it is not know for it's high quality taste. Robusto coffee beans that are used mostly for instant coffee and a blend with Arabica beans in espresso for a creamier foam.
Yields for Robusto coffee are about 1-2 pounds per bush. For more information, visit the Talk About Coffee web site.