Spring Grove arborvitae

Sun

Full sun to partial shade; growth is denser with good light.

Water

Moderate to high; keep the root zone evenly moist, especially during establishment and hot, dry weather.

Soil

Deep, moisture-retentive but well-drained soil. Tolerates clay if drainage is adequate, but struggles in very dry, shallow or persistently waterlogged ground.

Height

20-30 ft (6-9 m) in many garden descriptions; can exceed 40 ft (12 m) over time

Spread

10-15 ft (3-4.6 m), potentially wider with age

Foliage

Evergreen. Aromatic, flattened sprays of glossy, scale-like green leaves, with pale markings beneath. Selected for good winter colour, though exposed foliage can bronze or scorch in harsh conditions.

Growth

Moderate to fast once established, depending on moisture, soil and climate.

Care needed

Low

• Wildlife

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   7 ft (2 m)

2. After 1 year

   8 ft (2.3 m)

3. After 2 years

   9 ft (2.7 m)

4. After 3 years

   10 ft (3 m)

5. After 5 years

   12 ft (3.7 m)

About 16 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Native to

Canada

Growth rate

Fast

• Water deeply during dry spells for the first two growing seasons; established trees also need help during prolonged drought.
• Spread 2-3 in (5-8 cm) of organic mulch over the root zone, keeping it clear of the trunk.
• Plant with the root flare at soil level and allow room for the mature width.
• Feed in spring only if growth is weak and soil fertility is poor; avoid heavy nitrogen feeding.
• In cold climates, water before the ground freezes if autumn has been dry.

Pruning. Remove dead or damaged branches in late winter or early spring. For a hedge, trim lightly in late spring or early summer, keeping the base wider than the top; do not cut back into bare old wood, which usually does not regrow.

Early spring

Check for winter scorch, broken branches and loose ties; remove damaged growth once its condition is clear.

Spring

Plant while conditions are cool and the soil is workable; water thoroughly and mulch.

Late spring

Lightly trim hedges if needed, staying within leafy growth.

Summer

Check soil moisture during dry weather and inspect foliage for mites or browning.

Autumn

Replenish mulch and water deeply if rainfall has been low.

Winter

Keep de-icing salt away from the root zone and avoid piling salty snow against the foliage.

• Create a tall evergreen screen along a spacious boundary, allowing for its mature width.
• Use as a single pyramidal specimen in a large lawn or park-like garden.
• Provide a dark green backdrop for flowering shrubs, ferns and shade-tolerant perennials.
• Form a broad clipped hedge where there is room for regular access and maintenance.

Garden styles it suits: Traditional, Formal, Grand estate, Woodland, Pacific Northwest woodland and Winter interest.

Plant it with: Rhododendrons, Japanese maples, Oakleaf hydrangeas, Hostas, Western sword ferns and Japanese forest grass.

Wildlife: Dense foliage offers shelter and potential nesting sites for birds. Deer may browse the foliage, particularly in winter.

• Drought and winter scorch: water deeply during dry periods, mulch the root zone and shelter young plants from drying winds.
• Root rot in saturated soil: improve drainage or choose another site; do not leave roots standing in water.
• Spider mites: look for fine stippling and webbing during dry weather; rinse foliage and use a labelled treatment only if an active infestation persists.
• Deer browsing: western red cedar is not deer-proof; protect young trees with a substantial fence where browsing pressure is high.

Do not treat it as edible or livestock fodder. Foliage and especially concentrated leaf oil contain compounds that can be harmful if swallowed; sap or foliage may also irritate sensitive skin. Reliable species-specific poisoning information for cats, dogs and horses is limited, so keep clippings away from pets and grazing animals and seek veterinary advice after substantial ingestion.

• Eastern arborvitae (Thuja occidentalis)

  Its foliage undersides generally lack the conspicuous pale butterfly-shaped markings typical of western red cedar. Cultivar shapes overlap, so check the nursery label.

• Lawson cypress (Chamaecyparis lawsoniana)

  It bears small, rounded woody cones rather than the elongated cones with overlapping scales found on Thuja.

• Green Giant arborvitae (Thuja 'Green Giant')

  This vigorous hybrid often develops a narrower, more strongly conical outline, but foliage alone is not a dependable distinction; a reliable plant label is the best guide.

The species name plicata means folded or pleated, referring to the foliage, while arborvitae is Latin for tree of life.

Propagation. Propagate by semi-ripe cuttings in late summer, using a free-draining medium and humid conditions. Seedlings will not reliably retain the cultivar's characteristics.

Accepted botanical name

Thuja plicata

Native range

Alaska, Alberta, British Columbia, California, Idaho, Montana, Oregon and Washington.

Measured

Soil pH 5.1 to 7.1. Average height 2030 cm.

Sources: GBIF (CC BY 4.0) and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.