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 long does it take a saguaro to grow an arm?

Because saguaros grow so slowly, it might take 50 to 75 years for them to grow their first arms. Arms are important to them because they store extra water. After 100 years, they usually have several arms. After 200 years they have many arms.

How old is the oldest saguaro?

Old Granddaddy was about 300 years old when the saguaro cactus started to die in the 1990s. Old Granddaddy is the oldest known cactus ever in the world. Not only was Old Granddaddy old, it was a giant at over 40 feet tall and had 52 arms just before it died.