Giant redwood

Giant redwood: how do you recognise it?

Habit

Huge tree of 30–50 m; conical when young with branches down to the ground, later with a tall crown about 12 m wide on a massive trunk that flares at the base.

Needles

Scale-like needles 4–10 mm long, sharp and awl-shaped, spiralled around round, cord-like shoots; blue-green, with an aniseed scent when crushed.

Bark

Reddish-brown, fibrous and spongy, tens of centimetres thick on old trees: you can safely give it a punch.

Cones

Egg-shaped cones of 5–8 cm with shield-shaped scales.

Difference from dawn redwood

Dawn redwood has soft, flat needles that drop in autumn.

Difference from Japanese cedar

Japanese cedar (Cryptomeria) has longer, forward-curving needles and small, spiky cones.

Pruning: June–August

Identify by feature: Scales instead of needles

Looks like it, but isn’t

• Dawn redwood Metasequoia glyptostroboides: soft, flat needles that drop in autumn. Difference from dawn redwood
• Japanese cedar (Cryptomeria japonica): longer, forward-curving needles and small, spiky cones.

Why grow it?

• A monument for the future: few trees grow so big and so old.
• Beautiful, soft, reddish-brown bark and a crisp conical shape.
• The spongy bark is a favourite roosting spot for treecreepers.
• Little work: it needs hardly any pruning.

Giant redwood: where does it grow best?

• Full sun: in shade it grows thin and loses its lower branches.
• Any deep, free-draining soil; it doesn’t like waterlogging.
• The fallen needles acidify the soil under the tree.
• Allow for 30–50 m in height and a crown of 12 m or more: only for a park, an estate or a very large garden, well away from houses and services.

Light

Full sun

Legal basis

Any garden soil

Moisture

Normal

Size

40 m tall, 12 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Dawn redwood: Another giant of the cypress family, but one that drops its needles in autumn: together a superb parkland scene.
• Swamp cypress: A deciduous conifer for the edge of a pond in a park, with russet autumn colour.
• Cedar of Lebanon: Another monumental parkland tree, with broad, horizontal tiers.
• Rhododendron: Evergreen shrubs with large flowers in May, on the acid soil at the edge of the crown: a classic 19th-century parkland scene.

Good and bad companions

Goes well with

• Like the acid soil under this tree: heather, rhododendron, japanese skimmia, raspberry, highbush blueberry, witch hazel, broom, gorse
• Tolerate the shade under this tree: oregon grape, rhododendron, oleaster, japanese skimmia, garden privet, camellia, laurustinus, box-leaved honeysuckle

Giant redwood: when and how to plant it?

1. Plant in March–April or September–October; choose a young plant in a pot.
2. Pick an open spot with room all round: the crown must be able to grow right down to the ground.
3. Don’t plant deeper than it was in the pot and don’t add manure to the planting hole.
4. Water after planting and during dry spells in the first two summers.

Care

Watering

In dry spells for the first few years; after that it usually copes on its own.

Feeding

Not needed.

Lower branches

Keep the lower branches: they are part of its shape, and they keep the ground beneath cool.

Root zone

Leave the fallen needles where they are and don’t drive heavy machinery under the crown.

Tip: Only plant a giant redwood where it can grow 50 m tall and 12 m wide, even a hundred years from now. If you don’t have that space, admire one in a park or arboretum.

Giant redwood: when to prune it?

Pruning months: June–August.

When: Dead, diseased and broken branches can be removed at any time of year. If pruning is needed, do it in summer (June–August).

How:

• Don’t prune: the lower branches can stay right down to the ground.
• Only remove a second leader on a young tree, so it keeps a single straight trunk.

Caution: Don’t cut large branches out of an old tree and never top it: it would lose its shape for good.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Sowing

Let ripe cones open somewhere warm and dry, and sow the fine seeds thinly in spring on a tray of moist, sandy compost. Seedlings are prone to fungal disease: keep them airy.

Grafting

Cuttings root with difficulty; forms such as the weeping ‘Pendulum’ are grafted, and that is a job for the nursery.

Giant redwood: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Hardy in Belgium and the Netherlands.
• In winter the reddish-brown bark stands out best, among the bare broadleaved trees in a park.

Diseases and pests

• Branches browning and dying back: Often caused by a fungus that attacks weakened trees, for example after drought. Cut dead branches back into healthy wood and water young trees in dry summers.
• Shedding shoots: In autumn old, brown foliage shoots drop: that is normal.
• Lightning: As the tallest tree around, it is often struck by lightning; the top may then die. Never shelter under a tall, isolated tree during a thunderstorm.
• Too little space: It grows faster and wider than you expect. Pruning is no solution: plant it from the start where it has enough room.

Through the year

• March: Planting season for pot-grown plants starts.
• April: Sowing; last month for spring planting.
• June: Remove a second leader on a young tree.
• July: Water young trees in dry spells; summer pruning possible.
• August: Last month for summer pruning.
• September: Early autumn planting season.
• October: Old foliage shoots drop: normal.

What can you use it for?

Garden and landscape

Impressive parkland tree, only for very large gardens: it grows wider and taller than you think.

For wildlife

The soft bark is a favourite roosting spot for treecreepers.

Also used for

In America the brittle wood was mainly used for roof shingles and posts.

Good for wildlife

Birds

Berries, seeds or insects as food, or a place to nest.

Did you know?

• In California they live for more than 3000 years. The thick bark protects the tree against forest fires.
• The ‘General Sherman’ in California is over 80 m tall and has the greatest volume of any tree in the world.
• In England it is called ‘Wellingtonia’, after the Duke of Wellington, who died shortly before the tree reached Britain in 1853.
• The English named it Wellingtonia, after the Duke of Wellington. Americans felt that was no name for their national giant and proposed Washingtonia.
• The largest living tree in the world by volume is a giant redwood: General Sherman, in Sequoia National Park in California.