Bartlett Tree Experts: Giant Sequoia

Sequoiadendron giganteum

The Giant Sequoia is well known due to it's impressive height and girth, it is locally known as the "Californian Big Tree". The largest single stemmed tree in the world is a giant sequoia called General Sherman; it stands 83.8 m tall and is 11.1 m in diameter at the ground. S. giganteum is the last living member of the genus Sequoiadendron and one of three "Redwoods"; it is an endangered species. This endangered status is in part due to its interesting ecology, fire is an important part of the life cycle as the heat helps to releases the seeds from the cones, clears vegetation in the understory, and releases minerals into the soil.

Culture
Concerns
Management

Culture for Giant Sequoia

Giant sequoia trees grow in acidic to neutral soil (pH 5.5 to 7.5) that is deep, well drained, and sandy loam in texture. The soil should remain moist but not wet. The tree is sensitive to waterlogging and moderately tolerant to drought. Since the giant sequoia is an alpine species, it is both heat and cold hardy and full sun is required.

Concerns about Giant Sequoia

The giant sequoia does not tolerate wet soils and thus Phytophthora root rot is an issue. The giant sequoia is generally free of pests and disease although the canopy should be checked for signs of phloem feeders (such as aphids and scale). Despite the giant sequoia being an evergreen tree, leaf fall will occur, this is particularly noticeable during spring and autumn where internal leaves will fall from the tree (this is a natural process).

Management Practices for Giant Sequoia

Phytophthora infection can be treated by correcting drainage, a soil management program (RCX, biochar, phosphites, and mulch), and prescription fertilisers. Armillaria should be treated at the first sign of infection using a similar program with the addition of air spading and Trichoderma. Phloem feeders can be treated with a preventative winter wash (Bandu, Trident, Spray Oil) or appropriate PHC program.