Northern white cedar

Northern white cedar: how do you recognise it?

Habit

Evergreen conifer of 10–20 m (in gardens usually 3–10 m) with a narrow, conical crown about 4 m wide; as a hedge usually 1.5–3 m.

Foliage

Scale leaves in flat, fan-like sprays; dull green above, paler yellowish green below without white patches. Crushed, they smell strong and fruity, rather like apple. Often brownish in winter.

Bark

Reddish-brown to grey, in narrow, fibrous strips.

Cones

Upright, egg-shaped cones about 1 cm long with 8–10 thin scales; yellowish green at first, brown when ripe.

Difference from western red cedar

Western red cedar has glossy dark green foliage with white patches underneath that smells of pineapple, and becomes a large tree.

Difference from Lawson cypress

Lawson cypress has a white X pattern under the sprays, round cones and a drooping leader.

Pruning: May–June and August–September

Identify by feature: Scales instead of needles

Looks like it, but isn’t

• Western red cedar Thuja plicata: glossy dark green foliage with white patches underneath that smells of pineapple; becomes a large tree. Difference from western red cedar
• Lawson cypress Chamaecyparis lawsoniana: a white X pattern under the sprays, round cones and a drooping leader. Difference from Lawson cypress
• Thuja Thuja: the page for the whole genus, with what all thujas have in common.

Why grow it?

• A dense, evergreen hedge or windbreak that takes up little space.
• Forms for every garden: narrow columns such as ‘Smaragd’, globes such as ‘Danica’ and golden forms such as ‘Rheingold’.
• Grows in almost any soil, in sun or partial shade.
• Blackbirds and sparrows like to nest and shelter in a dense hedge.

Northern white cedar: where does it grow best?

• Sun to partial shade; in deep shade it becomes thin and bare.
• Almost any soil, including chalky soil, that neither dries out nor becomes waterlogged; in wet soil the roots rot.
• Shallow roots: on dry sandy soil a hedge struggles in dry summers.
• As a hedge or narrow column it fits in any garden; left to grow freely it becomes about 4 m wide.

Light

Sun or partial shade

Legal basis

Any garden soil

Moisture

Normal

Size

12 m tall, 4 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Snowy mespilus: White blossom in April, berries for the birds and fiery autumn colour against the dark hedge.
• Panicled hydrangea: Large, pale flower panicles in summer, lovely in front of a green hedge in sun or partial shade.
• Lesser periwinkle: Evergreen ground cover with small blue flowers for the shady strip in front of the hedge.

Good and bad companions

Goes well with

• Tolerate the shade under this tree: oregon grape, rhododendron, oleaster, japanese skimmia, garden privet, camellia, laurustinus, box-leaved honeysuckle

Northern white cedar: when and how to plant it?

1. Plant root-balled or pot-grown plants in September–October or in March–April.
2. For a hedge: 2–3 plants per metre, depending on size and cultivar.
3. Dig a wide trench, mix compost into the soil and plant at the same depth as before.
4. Water generously straight away and weekly during dry spells in the first year; a layer of mulch keeps the soil moist.

Care

Watering

Regularly in dry spells during the first two years; later too in long dry summers, as the roots are shallow.

Feeding

A little compost or organic fertiliser along the hedge in March–April.

Inside

In autumn the oldest scale leaves inside turn brown and drop: that is normal.

Winter colour

A brownish winter tint is normal and fades in spring; ‘Smaragd’ stays the best green in winter.

Tip: For a narrow hedge that needs little clipping, plant ‘Smaragd’: it stays naturally narrow and dense and keeps its green colour best in winter. ‘Brabant’ grows faster but becomes wider and needs more clipping.

Northern white cedar: when to prune it?

Pruning months: May–June and August–September.

When: Trim a hedge in May–June and late August, no later than mid-September so the new growth can harden off. Check first that no birds are nesting.

How:

• Only cut into the green part: bare, brown patches will not fill in again.
• Keep the hedge slightly narrower at the top than at the bottom, so the base gets light and stays green.
• Narrow columns such as ‘Smaragd’ hardly need clipping: just trim any shoots that stick out.

Caution: Check first that no birds are nesting, and don’t trim in bright sun or during drought.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

In August–September, pull off a side shoot 10–15 cm long with a heel and root it in cutting compost under glass or in a cold frame.

Northern white cedar: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Fully hardy.
• The scale leaves often turn brownish in winter and green up again in spring.
• Shake wet snow off hedges and columns, or the branches will splay apart. A loose tie around a column helps.

Diseases and pests

• Drought: Brown patches and bare sections after a dry summer, especially on sand. Water young hedges and mulch the soil; dead sections will not fill in again.
• Root rot: On wet soil plants turn brown and die (Phytophthora). Only replace them once the drainage has been improved.
• Thuja leaf miner: Brown shoot tips with small holes in spring: tiny caterpillars feeding inside the scale leaves. Clip off the brown tips; a healthy hedge will grow over them.
• Dog urine and road salt: Brown patches at the base of a hedge along the street. Rinse with plenty of water, and plant a new hedge a little further from the pavement.

Through the year

• March: Plant (March–April); compost along the hedge.
• May: First trim (May–June); check first that no birds are nesting. Look out for brown tips from the leaf miner.
• June: Trimming still possible; water in dry spells.
• July: Water during long dry periods.
• August: Second trim in late August; take cuttings.
• September: Last trim by mid-September at the latest; planting season begins.
• December: Shake wet snow off hedges and columns.

What can you use it for?

Garden and landscape

One of the most widely used hedging conifers, also in narrow columnar forms such as ‘Smaragd’ and in globe forms.

For wildlife

Dense hedges give nesting sites and shelter to blackbirds and sparrows.

Caution: Leaves and twigs contain thujone and are poisonous if eaten, also for horses and livestock.

Did you know?

• According to tradition, Jacques Cartier’s men were cured of scurvy in Canada in the winter of 1535–1536 with a tea made from this tree: hence ‘arbor vitae’, tree of life.
• It was one of the first North American trees to be planted in Europe, as early as the 16th century.
• On the cliffs of the Niagara Escarpment in Canada grow small, gnarled specimens that are more than a thousand years old.