Dawn redwood

Identification and origin

Metasequoia glyptostroboides belongs to the cypress family, Cupressaceae, alongside its close relatives bald cypress (Taxodium) and coast redwood (Sequoia). Its native range is limited to central China, in Chongqing, Hubei and Hunan. It has become locally naturalized in Great Britain and Italy.

Its story is unusual. The tree was first described from fossils at least 50 million years old and was thought to be extinct. Living trees were discovered in China in 1941; the species was formally described in 1948 and introduced to the United States in the late 1940s. Its species name means “resembling Glyptostrobus,” because it was first mistaken for Chinese swamp cypress. The common name “dawn redwood” refers to its ancient origins.

It is a large, conical to pyramidal tree with a fast growth rate. In cultivation it commonly reaches 62.5–98.5 ft tall and 15–24.5 ft wide.

• Needles: flat, pliable and soft to the touch, less than 1 in long, arranged in two opposite ranks on short deciduous branchlets, which gives the foliage a feathery, fern-like look. Light green as they emerge and deep green in summer, they turn coppery to russet brown in fall, then drop along with their branchlets.
• Buds and branchlets: opposite, in pairs at the base of the deciduous branchlets. This opposite arrangement sets it apart from bald cypress, whose needles are alternate; the two trees are often confused, especially in fall, when both turn russet and shed their branchlets.
• Bark and trunk: reddish-brown to orange-brown, fibrous bark that peels in long strips and becomes deeply fissured with age. The base of the trunk broadens into buttresses and develops fluting, sometimes dramatically.
• Cones: each tree bears both sexes. Female cones are rounded to egg-shaped, up to 1 in long, and hang from long stalks; green at first, they turn brown as they ripen. Male cones are globe-shaped and about 1 in long.

Among the cultivars, ‘Gold Rush’ has golden-yellow foliage and a narrow habit; ‘Ogon’, ‘Miss Grace’ and ‘Hamlet’s Broom’ are also grown.

Light

Plant it in full sun, with at least six hours of direct sunlight a day. It handles exposed or sheltered sites facing south, west or east. It tolerates partial shade, but full sun remains the ideal, in the ground and as a bonsai.

Watering

Dawn redwood likes moist to wet soil. It copes with occasionally soggy ground, thrives beside ponds and water gardens, and even tolerates brief flooding. Once well established, it is moderately drought tolerant, though it then grows more slowly.

Rather than following a schedule, check soil moisture deep down during hot, dry weather, especially for a young, recently planted tree.

In a container or as a bonsai, its needs are much higher: in summer the mix should stay moist. Still, don’t let it sit in standing water, which encourages root rot in a pot.

Potting mix

It prefers deep, moist, well-drained soil, neutral to slightly acidic and rich in organic matter. It also grows in clay, loam or sandy soil. It tolerates chalky or dry soil, but grows more slowly there, and a high pH can cause problems: on very alkaline ground, bald cypress is the more forgiving choice. Avoid compacted soils that stay poorly drained all the time.

Temperature

This is a very cold-hardy tree, grown in USDA zones 4a to 8b, and it withstands continental winters below -4 °F. It does not handle early fall freezes well, however. In a pot, its roots are far more exposed to frost than those of a tree in the ground: protect the root ball in hard freezes.

It tolerates urban pollution, which makes it a good street tree wherever there is enough room.

Repotting

Dawn redwood transplants easily and roots quickly. In the garden, choose a spot with room to grow, because it gains size fast.

In a pot, its vigorous roots soon fill the container: repot in spring, before bud break, about every two years, shortening the roots substantially. The mix should hold enough water while still draining well.

Pruning

In the ground it needs almost no pruning: let it develop its natural pyramidal form. Remove only deadwood or a damaged branch. After a cut, the tree pushes many new buds, especially around pruning scars, which makes it well suited to bonsai, where it is trained as a formal upright or a forest planting.

Propagation

• Seed: the simplest method. Sow seed collected from ripe cones.
• Cuttings: semi-ripe or hardwood cuttings both work.
• Air layering: possible, especially to get a tree to train as a bonsai quickly.

Common problems

Dawn redwood is known for being nearly free of serious pests and diseases. Japanese beetles (Popillia japonica), where present, can eat the foliage. Cankers can develop on branches, and honey fungus, a root fungus, occasionally attacks it. Deer generally leave it alone.

Don’t worry when the needles turn brown and drop in fall: this is a deciduous conifer, and it is not a sign of disease. On the other hand, needles that brown in midsummer can have several causes, such as soil that is too dry, waterlogged roots or a pest: the same symptom can have different origins, so check the soil and branchlets before drawing conclusions.

Toxicity

No toxicity has been reported for dawn redwood: it does not appear among the plants listed as toxic to dogs and cats.