Take one (or more, if you wish) second and think, given the following information: the trees known as Giant Sequoias take about 12 years just to produce cones to seed. Which means 12 years just to be able to reproduce. The growth rate depends on soil composition, environment, age, etc. and for general tree growth rate, the Giant Sequoias are quite rapid. However, studies conducted for the National Park Service determined that General Sherman, the most renowned Giant Sequoia, has only grown three inches in diameter since 1931. General Sherman, when this study was done, was 272 feet high, over 30 feet in diameter, over 100 feet in circumference, and is currently estimated to be 2,300-2,700 years aged.
Now, how long did it take for that tree reach that size?