Sequoiadendron giganteum (giant sequoia)

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Sequoiadendron, Genus, giganteum, Species,

Genus & species

HardinessZones 6–8

Overview

Sequoiadendron is a genus of evergreen coniferous trees in the cypress family containing a single living species, the giant sequoia (Sequoiadendron giganteum). Mature trees reach 165-280 feet (50-85 m) tall with trunk diameters of 20-26 feet (6-8 m). The trunk is columnar and buttressed at the base, clad in fibrous, reddish-brown bark 24-36 inches (60-90 cm) thick. The crown is conical in youth, becoming rounded and irregular with age as lower branches are shed. Foliage consists of awl-shaped, scale-like leaves 0.1-0.25 inch (3-6 mm) long, blue-green, arranged spirally and overlapping along the shoots. Seed cones are egg-shaped, 1.5-3 inches (4-7 cm) long, maturing over two seasons and often remaining green and closed on the tree for up to 20 years. Trees grow slowly to moderately after establishment and can live more than 3,000 years. Heat from fire opens the cones and clears competing vegetation for seedlings. The shallow, wide-spreading root system leaves large specimens prone to windthrow on exposed sites, and mature trees decline under prolonged drought.

Native Range

The single living species is native to a limited range on the western slopes of the Sierra Nevada in California, occurring in about 75 disjunct groves between 4,600 and 7,000 feet (1,400-2,150 m) elevation. It grows in mixed conifer forest on moist, well-drained granitic soils.

Suggested Uses

Planted as a specimen and avenue tree in large parks, arboreta, and estates in temperate regions, spaced at least 30-50 feet (9-15 m) from structures and other trees. The eventual size leaves it unsuited to small gardens. Outside its native range it is grown in western Europe and the Pacific Northwest.

How to Identify

Distinguished from coast redwood (Sequoia sempervirens) by awl-shaped, scale-like blue-green foliage rather than flat needles, and by egg-shaped cones 1.5-3 inches (4-7 cm) long. Bark is reddish-brown, deeply furrowed, fibrous, and 24-36 inches (60-90 cm) thick. The trunk is strongly buttressed and columnar, carrying a rounded crown on mature trees.

Appearance

Size & Dimensions

Height165' - 280'

Width/Spread30' - 60'

Colors

Foliage Colors

blue green

green

Fall Foliage Colors

no change

Bloom Information

As a conifer, Sequoiadendron produces pollen and seed cones rather than flowers. Pollen cones release pollen in late winter to early spring, typically February through April. Seed cones take two seasons to mature and may persist closed on the tree for up to 20 years, opening after fire or drying.

Detailed Descriptions

Foliage Description

blue-green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0 (Acidic to neutral)

3579

Soil Types

loam sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Care & Maintenance

Care Guide

Grows in full sun in deep, moist, well-drained soils and needs consistent moisture during establishment. Mature trees are drought-sensitive compared with many western conifers and decline in prolonged dry spells. Hardy in USDA zones 6-8, tolerating temperatures to about -10°F (-23°C), though foliage may brown in cold, dry wind. The shallow, spreading root system limits stability on exposed or shallow soils. Few pests affect the species, but Botryosphaeria canker can damage drought-stressed trees. Trees need wide spacing to accommodate their eventual size.

Pruning

No routine pruning is required, and the species develops its form without intervention. Lower branches are shed naturally as the tree ages. Dead or damaged limbs can be removed in late winter. Topping eliminates the natural crown form and produces weak regrowth.