The Rainbow Eucalyptus (Eucalyptus deglupta) is a towering, evergreen species renowned for its vibrant, multi-hued bark. It is the only eucalyptus species native to the northern hemisphere, originating in the tropical rainforests of the Philippines, Indonesia, and Papua New Guinea. The striking colors—streaks of green, red, orange, and blue—are revealed as the outer bark continuously peels away in strips. This dramatic visual feature makes the tree a highly sought-after ornamental specimen.
Specific Growth Metrics
The Rainbow Eucalyptus is classified among the fastest-growing tree species globally. Under optimal conditions, a young tree typically gains between 3 and 5 feet in height per year. In its native, consistently humid tropics, this rate can accelerate, occasionally reaching 8 to 10 feet in a single year.
The most impressive growth spurts occur during the juvenile phase, generally within the first decade after planting. One specimen grown in a tropical environment reached 33 feet (10 meters) in height in just 18 months. After this initial growth, the rate of vertical gain often slows, but the tree continues to increase its trunk diameter and overall mass substantially.
Environmental Factors That Maximize Growth
Achieving maximum growth requires mimicking the tree’s native rainforest environment, characterized by consistent warmth and abundant moisture. The tree must have access to full, direct sunlight for the majority of the day. While it can tolerate partial shade, the best growth rates and vivid bark coloration depend on ample solar exposure.
Consistent, high levels of water are necessary for this species. The soil should be kept consistently moist but must also be extremely well-draining to prevent waterlogging and root rot. The preferred growing medium is rich, loamy soil with a slightly acidic to neutral pH.
Because of its fast growth, the Rainbow Eucalyptus is a heavy feeder that rapidly depletes soil nutrients. Young trees benefit from regular fertilization, often with a balanced, slow-release product applied in the spring. Providing these ideal inputs promotes the impressive yearly height gains the species is known for.
Mature Size and Climate Requirements
The ultimate size of the Rainbow Eucalyptus depends heavily on the growing climate. In its native habitat, such as the tropical forests of New Guinea and the Philippines, the tree regularly exceeds 200 feet in height, sometimes reaching up to 250 feet. Outside of its native range, in cultivated settings, it typically matures to a substantial height of 100 to 125 feet.
This species has extremely strict climate requirements that dictate where it can survive and maintain its rapid growth. It thrives in tropical and subtropical regions, generally limited to United States Department of Agriculture (USDA) Hardiness Zones 10 through 11. The tree is highly intolerant of cold temperatures; prolonged exposure to freezing conditions will severely damage or kill the tree. Therefore, the impressive growth rates discussed are only possible in environments that are reliably frost-free and provide year-round warmth.