average lifespan of cactus
An adult saguaro is generally considered to be about 125 years of age. It may weigh 6 tons or more and be as tall as 50 feet. The average life span of a saguaro is probably 150 - 175 years of age. However, biologists believe that some plants may live over 200 years.
How Saguaros Grow. Saguaros are a very slow growing cactus. In Saguaro National Park, studies indicate that a saguaro grows between 1 and 1.5 inches in the first eight years of its life. These tiny, young saguaros are very hard to find as they grow under the protection of a nurse tree, most often a palo verde, ironwood or mesquite tree.