10 Giant Saguaro Cactus Seeds /Carnegiea Gigantea / Classic Southwestern Cacti When the average American thinks of a cactus, he or she probably pictures a giant saguaro with a central column and two arms. This Sonoran desert cactus is symbolic of the southwestern U.S. and its huge white blooms have been adopted as the state flower of Arizona. To see saguaros in their natural grandeur you can visit places like Saguaro National Park. Much of the fascination with the saguaro probably comes from its impressive stature, which towers thirty-five to even fifty feet in height at maturity, making it the largest cactus in the United States. Despite its size, saguaro is actually very slow-growing, and it takes about 150 years for a cactus to reach its full size and 40 years flower. A forty-year-old cactus is actually not too old when you consider that saguaros exist that are 200 years in age. It takes about 150 years for a cactus to reach its full size and 40 years flower. A forty-year-old cactus is actually not too old when you consider that saguaros exist that are 200 years in age. The fruit of the saguaro can be eaten as it was by members of the Pima and Papagos tribes and the fruit and syrup from the cactus can be used to make alcoholic beverages. The saguaro is a favorite among cactus collectors, although wild harvest of the cactus has been made illegal. Its slow growth and the low survival rate of seedlings in the harsh desert environment make it hard for the species to compete against the demand by cactus collectors. According to estimates, a mature cactus can produce up to ten million seeds in a single year, yet it is likely that not one will make it into a stable plant. Fortunately, it grows quickly and easily from seed in cultivation and is relatively easy to maintain.