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. Some groves are on glacial outwash from granite. Other common parent materials include schistose, dioritic and andesitic rocks.
Giant sequoia grows best in deep, well-drained sandy loams.
It occurs with higher frequency on mesic sites, such as drainage bottoms and meadow edges. Soil pH ranges from 5.5 to 7.5, with an average of about 6.5. Long-term site occupancy develops soil of high fertility, good base status, and low bulk density. Giant sequoia has adapted to keep its crown higher than that of its associates. Current data does not indicate that any enlargement of giant sequoia groves is taking place.