Why is my arborvitae turning brown?

Browning can be caused by drought, winter burn, or root rot from overwatering.

Can I prune it into a shape?

Yes, it responds well to shearing, but only prune the green growth.

Plant guide

Northern white cedar.

Thuja occidentalis

Pronounced THOO-yuh ok-sih-den-TAL-iss

Also known as American Arbor-Vitae, American arborvitae, Arbor-vitae, Arborvitae, Eastern Arbor-vitae, Eastern Arborvitae, Eastern White Cedar, Eastern White-cedar

Thuja occidentalis — Photo by Marek Hrušovský (CC0) via gbif

This hardy evergreen is a classic choice for privacy screens and hedges in cooler climates. It features a dense, conical shape that stays green all year round. You will love how it adds structure and a fresh scent to your garden.

At a glance

Care level: Easy
Plant type: Coniferous evergreen tree
Light: Full sun to partial shade
Indoor light: Bright indirect
Water: Every 7 to 14 days
Mature size: 40 to 60 feet
Growth rate: Medium
Hardiness: USDA 2 to 7
Bloom time: Early to mid spring

Care

Plant this tree in a spot with well draining soil and plenty of room to spread out. Keep an eye out for browning foliage which often signals a need for more moisture or protection from harsh winter winds. Regular mulching helps keep the roots cool and hydrated.

Watering: Water deeply during dry spells to keep the soil consistently moist but not waterlogged.
Feeding: Apply a balanced slow release fertilizer once in early spring before new growth starts.
Pruning: Trim lightly in late spring to maintain shape, but avoid cutting into old wood that lacks needles.
Repotting: If growing in a container, move to a slightly larger pot every few years to refresh the soil.
Soil: Moist, well drained, loamy soil
Soil pH: 6.0 to 8.0
Temperature: -40 to 30°C
Humidity: 40 to 70%
Drought tolerance: Moderate
Lifespan: Perennial, typically 50 to 150 years
Fragrance: Light
Deer and rabbits: Low

Signs it needs repotting

Roots growing out of the drainage holes
Water running straight through the pot without soaking in

Safety

People: The foliage contains thujone, which can cause digestive upset or more serious symptoms if consumed.
Pets: The foliage contains thujone and is considered mildly toxic to cats and dogs. Eating it can cause vomiting and diarrhea.
Children: Keep small children away from the foliage as ingestion can cause stomach pain.
Contact allergens: Handling the foliage may cause mild skin irritation in sensitive individuals.
Airborne allergens: The pollen can be a moderate trigger for those with seasonal allergies.
Edibility: This plant is not intended for consumption and can be toxic if ingested in large quantities.

How to identify it

Fan shaped sprays of scale like leaves
Conical growth habit when young
Reddish brown bark that peels in strips
Small oblong cones with few scales

Height: 3 to 18m
Spread: 1 to 4.5m
Leaves: green, yellow-green, evergreen
Flowers: yellow, brown, 0.5 to 1cm
Fruit: brown, Autumn

Problems to watch for

Bagworms · These caterpillars create silk bags covered in foliage and can defoliate branches.
Spider mites · Tiny pests that cause foliage to turn yellow or bronze during hot, dry weather.
Root rot · Often caused by poorly drained soil, leading to browning and eventual plant death.

By symptom

Plant problems by symptom

Check your northern white cedar from a photo

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Growing it

Propagation: cuttings, seed
When to plant: spring, autumn
Overwintering: Ensure the soil is moist before the ground freezes. Apply a layer of mulch to protect the roots from temperature fluctuations.
In containers: It can grow in large containers for several years, but prefers being in the ground.

Cuttings

Take a 10 cm cutting from a healthy branch in late summer.
Dip the end in rooting hormone.
Place in a moist, well draining potting mix.
Keep in a humid environment until roots develop.

Plant these in groups to create a microclimate that retains moisture and blocks wind for smaller plants.

Grows well with

Hosta · They enjoy the same partial shade and moist soil conditions.
Bleeding Heart · These perennials add a nice contrast to the evergreen backdrop.

Similar species

Western Red Cedar · It is a much larger tree with similar foliage but different native range.

Science

Family: Cupressaceae
Genus: Thuja
Order: Pinales
Class: Pinopsida
Native range: Eastern North America
Conservation: This species is widely distributed and not currently of conservation concern.

It thrives in cool, moist environments and often grows in swamps or on limestone cliffs.

Value to wildlife: winter shelter for birds, nesting site
Pollinators: beetles
Uses: privacy screening, windbreak, ornamental hedge, topiary

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 7/9
Light: 6/9
Temperature: 3/9
Moisture: 6/9
Nutrients: 5/9

Taxonomy resolved against GBIF.

Questions people ask

Why is my arborvitae turning brown?: Browning can be caused by drought, winter burn, or root rot from overwatering.
Can I prune it into a shape?: Yes, it responds well to shearing, but only prune the green growth.

Where the name comes from

The name Thuja comes from the Greek word for an aromatic wood, while occidentalis means western.

Good to know

It is commonly known as Northern White Cedar, though it is actually a juniper relative.
The wood is highly rot resistant and was used for canoe building.
It can live for several hundred years in the right conditions.

Also in

Plants toxic to cats and dogs

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This guide was generated with AI on October 19, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.