Saguaro: 1 saguaro produces tens of thousands of seeds in a year - lifetime: 175-200 years! After 15 years it may be 15 inches tall - after 30 years it begins to flower and produce fruit. By 50 years it may be 7 feet tall - after 75 years it may sprout its first branches or arms. By 100 years it may reach 25 feet. Saguaro live 150 years and more, towering 50 feet and weighing 16000 ponds or more!