The upper part of the crown of any mature giant sequoia invariably produces a greater abundance of cones than its lower portions. A mature giant sequoia has been estimated to disperse from 300,000 to 400,000 seeds per year. Seed dispersal results from seed falling from the tree-top, insect and rodent activity, or by cones falling to the ground. April, May, September, and October temperatures are best for early development. Soil moisture conditions and seedling survival are generally better in spring than during any other season.
Light conditions are generally best for growing at one-half full sunlight.
Beyond the seedling stage, giant sequoia unhindered by an overstory continues to grow at the same rate as its competitors. Lower branches die fairly readily from shading, but trees less than 100 years old retain most of their dead branches. Low temperatures seem to be the limiting factor for giant sequoia at the upper elevational limits of its range, as well as in areas with severe winters where the species has been introduced. Giant sequoia is found in a humid climate characterized by dry summers. Most precipitation comes in the form of snow between October and April.