Thuja (Arbor vitae) - How to Grow & Care Guide

Plant Snapshot

Common Name: Thuja
Latin Name: Arbor vitae
Hardiness Zones: USDA zones 2–8 depending on species. Colder limits can cause dieback in less hardy species. In warmer zones some species may be stressed and more pest prone.
Typical Height: Typically 10–60 ft (3–18 m) depending on species and cultivar.
Typical Spread: Typically 10–20 ft (3–6 m) at maturity for taller tree forms. Cultivars may be narrower.
Bloom Period: No showy flowers produces small pollen and seed cones usually produced in spring.
Soil Preferences: Prefers moist fertile well drained soil. Tolerates clay and periodic wetness but dislikes waterlogged poorly drained sites that cause root decline. Neutral to slightly acidic pH is ideal.
Light Preferences: Full sun to part shade. Full sun promotes the densest growth while deep shade can cause thinning and sparse foliage.
Toxicity: Contains aromatic compounds and thujone in essential oils that can be toxic if ingested and may cause skin or digestive irritation. Confirm pet and human toxicity details with local poison control and veterinary sources.
Propagation: Propagate by seed and by cuttings. Semi hard or softwood cuttings are commonly used to reproduce cultivars. Layering and grafting are used for some forms.

Key Facts

Evergreen conifer commonly called arborvitae.
Foliage is scale like and aromatic when crushed.
Used widely for hedges screens and windbreaks.
Native to North America and eastern Asia.
Produces small woody cones rather than showy flowers.
Prefers moist fertile soil but tolerates a range of soils.
Grows in a wide range of sizes from compact shrubs to tall trees.
Propagated by seed and cuttings for landscape and cultivar production.

Thuja, commonly called arborvitae, is an evergreen conifer prized for dense, scale like foliage and reliable screening. It ranges from compact shrubs to tall trees and produces small woody cones in spring, so choose species and cultivar to match space and hardiness.

Identification

Thuja has flattened sprays of scale like leaves that release a distinct aroma when crushed and bears small woody cones rather than showy flowers. Native to North America and eastern Asia, forms range from low growing landscape cultivars to tall timber trees. Check species or cultivar labels before relying on size or cold tolerance.

Best uses and where to grow

Use Thuja for formal hedges, privacy screens, windbreaks and specimen planting where evergreen structure is wanted year round. Many cultivars fit narrow urban sites while larger species work in rural windbreaks. Hardiness varies by species and cultivar with an overall USDA range from zone 2 to zone 8, so confirm the selection for your climate.

Soil and light

Thuja prefers moist fertile, well drained soil and tolerates clay and periodic wetness, but will decline in waterlogged conditions. A neutral to slightly acidic soil pH is ideal. Plant in full sun to part shade for the densest growth and avoid deep shade that causes thinning and sparse foliage.

Planting and spacing

Set the top of the root ball level with the surrounding soil and mulch to conserve moisture and suppress weeds. Space taller tree forms roughly according to mature spread, commonly about 10 to 20 feet apart, and choose tighter spacing for narrow cultivars. Avoid low spots where water stands and reduces root health.

Watering and common problems

Consistent moisture during establishment supports dense foliage and fewer winter browning issues. Prolonged waterlogging leads to root decline and dieback while drought stress causes tip browning and thinning. In climates at a species limit, winter damage or stress can increase susceptibility to pests and decline, so match species to site conditions.

Pruning and after flowering care

Prune Thuja to maintain hedges and shape, removing new growth lightly to retain a dense habit. Because forms and responses vary by cultivar, avoid cutting back into old bare wood where foliage may not regrow. Clean up fallen branches and cones to reduce disease and pest habitat.

Controlling spread and site impact

Thuja does not usually naturalize aggressively, but taller forms cast deep shade and dense roots that can suppress underplantings. Plan spacing and underplant tolerant shade lovers if you want layered beds. Regular pruning and thinning keep a hedge from becoming overly dense and reduce crowding of nearby plants.

Propagation

Propagate Thuja by seed or by cuttings depending on whether you need true to cultivar plants. Semi hard or softwood cuttings are commonly used to reproduce named cultivars while layering and grafting are used for some forms. Choose propagation method based on the cultivar and your goal for uniformity.

Safety and toxicity

Thuja contains aromatic compounds and components such as thujone that can be toxic if ingested and handling may cause skin irritation in sensitive individuals. Toxicity varies by species, plant part and amount, so confirm pet and human risk with local poison control or ASPCA resources before planting in areas used by children or pets.

Frequently asked questions

How fast does Thuja grow?: Growth rate varies widely by species and cultivar from slow for compact landscape types to relatively fast for some tree forms. Check the specific cultivar for expected habit and rate.
What USDA zones do Thuja grow in?: Hardiness depends on species and cultivar. The overall range across Thuja species commonly falls between USDA zones 2 and 8, so verify the listed zone for your chosen plant.
Can Thuja be used for a privacy hedge?: Yes. Many Thuja cultivars are used as hedges and screens. Select a cultivar with the desired mature height and space plants according to their eventual spread.
Are Thujas safe for pets?: Thujas can be potentially toxic if ingested. The severity depends on species and amount consumed. Consult local poison control or veterinary resources for specific guidance.
When do Thujas produce cones?: Thuja produces small pollen and seed cones, with cone development commonly initiated in spring. Exact timing varies by species and local climate.