Red cedar trees bear a unique distinction. Unlike trees such as magnolia and pine, cedar trees are not a single genus of plants. Rather, cedar species belong to a number of genera. Genera to which North American species of red cedar belong include Thuja and Juniperus. Though trees such as western red cedar and eastern red cedar are largely unrelated species, they have somewhat similar growth rates because they are large trees native to environments with comparable climates and moisture content.
Eastern Red Cedar
Easter red cedar (Juniperus virginiana) is a species of tree native to Eastern and Central North America. The eastern red cedar has a moderate growth rate, according to the University of Connecticut. The U.S. Forest service reports that on average, trees aged 26 to 30 are 18 to 26 feet tall, expressing a growth rate of approximately 7 inches to 1 foot per year. Mature trees aged 50 and older are usually 40 to 50 feet tall though they may reach 120 feet. Thus, growth rates slow considerably after the first 30 years of a specimen's life.
Western Red Cedar
Western red cedar (Thuja plicata) is a species of tree native to the West Coast of the United States and Canada. The University of Connecticut states that the growth rate of the species is moderate. According to the U.S. Forest Service, trees are generally 70 to 100 feet tall at maturity, though old growth specimens can be as tall as 200 feet. Old growth trees are those believed to be at least 1,000 years old. Thus, while western red cedar reaches a mature height at a moderate growth rate, it may continue at a slow growth rate for centuries.
Western red cedar is described as an adaptable species. The U.S. Department of Agriculture explains that trees can adapt to a number of growth environments, including shade growth beneath large, established trees. In such conditions, growth rate is slow but the specimen will grow steadily over long periods.
The eastern red cedar has an average moderate growth rate, though it can grow more quickly or slowly under certain circumstances. Conditions affecting eastern red cedar growth include soil and site quality, competition from other species and the density of specimens.
Mature eastern red cedar produces a good crop of seed every two to three years. When grown from seed in nurseries, eastern red cedar will take one to two years to reach an appropriate size for replanting. Trees taking root in the wild will develop large, strong root systems in rocky and shallow soil. However, specimens in such conditions will take longer to grow upward than those in standard soil.
Western red cedar trees begin producing cones between 10 and 20 years of age. Optimal cone crops begin when trees reach 70 to 80 years and can continue for centuries -- the species can live for nearly 1,500 years. Red cedar will grow well in soils with high mineral content.