Thuja occidentalis 'Nigra' (White cedar 'Nigra')

Botanical name

Thuja occidentalis 'Nigra'

Other names

White cedar 'Nigra', Eastern white cedar 'Nigra', Northern white cedar 'Nigra', American arborvitae 'Nigra', Eastern arborvitae 'Nigra'

Genus

Thuja Thuja

Variety or Cultivar

'Nigra' _ 'Nigra' is a dense, narrowly conical, evergreen, coniferous tree with reddish-brown, exfoliating bark, flattened sprays of ovate, scale-like, aromatic, dark green leaves and ovoid, female cones with paired, smooth scales.

Native to

Garden origin

Foliage

Evergreen

Habit

Dense, Narrowly conical

Toxicity

Contact with the skin may cause irritation.

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Colour

Foliage

Dark-green in All seasons

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How to care

Watch out for

Specific pests

Scale insects

Specific diseases

Canker

General care

Pruning

Little to no pruning required.

Propagation

Sow seed in a cold frame in late winter or early spring.

Propagation methods

Seed, Semi-hardwood cuttings

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Monthly care advice

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Where to grow

Thuja occidentalis 'Nigra' (White cedar 'Nigra') will reach a height of 9m and a spread of 3m after 20-50 Years.

Suggested uses

Low Maintenance, Beds and borders, Architectural, Rock, Specimen tree

Cultivation

Grow in fertile, moist but well-drained soil in full sun. Tolerates light shade. Needs protection from drying winds, particularly when young.

Soil type

Chalky, Clay, Loamy, Sandy (will tolerate most soil types)

Soil drainage

Moist but well-drained, Well-drained

Soil pH

Acid, Alkaline, Neutral

Light

Full Sun

Aspect

North, South, East, West

Exposure

Exposed, Sheltered

UK hardiness Note: We are working to update our ratings. Thanks for your patience.

Hardy (H4)

USDA zones

Zone 8, Zone 7, Zone 6, Zone 5, Zone 4, Zone 3

Defra's Risk register #1

Plant name

Thuja occidentalis 'Nigra' (White cedar 'Nigra')

Common pest name

Scientific pest name

Lamprodila festiva

Type

Insect

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

5

Impact (1 is very low - 5 is very high)

3

General biosecurity comments

Beetle that is native to Europe; whose larvae damage certain ornamental conifer species. Absent in the UK; so industry should source plants carefully and monitor for its presence.

Defra's Risk register #2

Plant name

Thuja occidentalis 'Nigra' (White cedar 'Nigra')

Common pest name

Cypress twig; borer

Scientific pest name

Argyresthia cupressella

Type

Insect

Current status in UK

Present (Widespread)

Likelihood to spread in UK (1 is very low - 5 is very high)

3

Impact (1 is very low - 5 is very high)

3

General biosecurity comments

Has spread following introduction; little evidence of significant damage. Stakeholder groups may wish to monitor.

Defra's Risk register #3

Plant name

Thuja occidentalis 'Nigra' (White cedar 'Nigra')

Common pest name

Western hemlock wood stainer

Scientific pest name

Gnathotrichus sulcatus

Type

Insect

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

1

Impact (1 is very low - 5 is very high)

3

General biosecurity comments

EU regulated pest of conifers and regulations appear to be effectively mitigating against the risk of entry.

About this section

Our plants are under greater threat than ever before. There is increasing movement of plants and other material traded from an increasing variety of sources. This increases the chances of exotic pests arriving with imported goods and travellers, as well as by natural means. Shoot is working with Defra to help members to do their part in preventing the introduction and spread of invasive risks.

Traveling or importing plants? Please read "Don't risk it" advice here

Suspected outbreak? Click here for contact details to report to the relevant authority.

Date updated: 7^th March 2019 For more information visit: https://planthealthportal.defra.gov.uk/