When it comes to exotic fruit trees, the Ruby Supreme Guava Tree tops the list. The trees are easy to grow, can tolerate drought, and thrive in almost any soil type. The fruit of the Ruby Supreme Guava Tree is small (between two and four inches long,) round or slightly elongated, and has smooth, ruby-red pulp that is both fragrant and sweet. Ruby Supreme Guava Trees are self-fertile and even a six foot tree on a patio can produce dozens of fruit. Ruby Supreme Guava Trees are tropical, and do best in USDA Growing Zones 8 to 11. Mature, healthy trees can survive short periods of freezing temperatures if protected, but if you are growing a Guava in a colder area, it is best to grow the tree in a container and bring it indoors in winter months.