Emerald Green Arborvitae (Thuja occidentalis 'Smaragd')

Plant Snapshot

Common Name: Emerald Green Arborvitae
Latin Name: Thuja occidentalis 'Smaragd'
Hardiness Zones: USDA zones 3–7
Typical Height: About 10–15 ft (305–457 cm)
Typical Spread: About 3–4 ft (91–122 cm)
Soil Preferences: Prefers moist, fertile, well drained soil, slightly acidic to neutral pH; tolerates heavier clay and periodic wetness but not standing water
Light Preferences: Full sun to part shade; too much deep shade causes thinning of foliage
Toxicity: Contains compounds that can be toxic if ingested; may cause gastrointestinal upset and more serious signs in large doses. Avoid livestock access and keep pets from chewing foliage. Handling may irritate sensitive skin
Propagation: Propagate by semi ripe or hardwood cuttings for true-to-type plants; layering and grafting also used. Seed propagation will not reliably reproduce cultivar traits

Key Facts

Narrow, dense, pyramidal evergreen used for hedges and screens
Typical mature height about 10–15 ft (305–457 cm)
Typical mature spread about 3–4 ft (91–122 cm)
Prefers full sun to part shade
Prefers moist, fertile, well drained soil and tolerates clay
Moderately slow to moderate growth rate
Can suffer winter browning or dieback in exposed dry sites
Cultivar maintained by cuttings to preserve form

Emerald Green Arborvitae (Thuja occidentalis ‘Smaragd’) is a narrow dense pyramidal evergreen commonly used for formal hedging and privacy screens. It typically reaches about 10 to 15 ft tall with a 3 to 4 ft spread and prefers moist well drained soil in full sun to part shade.

Identification and size

This cultivar has a tight upright form with bright green flattened foliage that stays dense when grown in sun. Typical mature height is about 10 to 15 ft and typical spread is about 3 to 4 ft. The narrow habit makes it easy to recognize in rows or as single specimen plants.

Best uses and where to grow

Use Emerald Green Arborvitae for narrow privacy screens small formal hedges and foundation plantings where vertical presence is needed without wide spread. It performs well in landscapes across cool and temperate gardens matched to its hardiness. Avoid deep shade where the foliage will thin and screening value will decline.

Planting and spacing

Plant in a location with several hours of sun each day and soil that stays moist yet drains. For a continuous screen space plants about 3 to 4 ft apart so crowns meet as they mature. Set the root ball level with the surrounding soil and mulch to conserve moisture and moderate soil temperature.

Soil light and watering

Emerald Green Arborvitae prefers moist fertile well drained soil and will tolerate heavier clay when it drains. Keep soil consistently moist to prevent browning and dieback that can occur from extended dry conditions. Full sun to part shade is best and too much deep shade causes thinning of foliage.

Winter and maintenance care

In exposed dry sites this cultivar can suffer winter browning or dieback so protect roots with a generous mulch layer and avoid late season fertilizing that encourages tender growth. Prune lightly to maintain shape and to remove dead wood. Severe pruning into old wood may not regenerate foliage as readily.

Propagation

To retain the true form of ‘Smaragd’ propagate by semi ripe or hardwood cuttings using rooting hormone and cool moist conditions. Layering and grafting are other reliable methods. Seed will not be true to the cultivar so avoid seed propagation when a specific form is required.

Frequently asked questions

How fast does Emerald Green Arborvitae grow?: Growth is moderately slow to moderate depending on site fertility and moisture. Expect steady but not rapid gain in height each year.
What hardiness zones are suitable?: This cultivar is generally listed for USDA zones 3 to 7. Local conditions at zone edges can affect winter survival and growth.
Is Emerald Green Arborvitae toxic to pets?: Thuja contains compounds that can be toxic if ingested and may cause gastrointestinal upset. Keep pets and livestock from chewing foliage and check with local poison control for guidance.
How close should I plant for a hedge?: For an even screen place plants about 3 to 4 ft apart so the narrow crowns form a continuous barrier as they mature.
Will it suffer winter browning?: Yes in exposed dry sites winter browning and dieback can occur. Mulch roots and provide consistent moisture to reduce winter stress.
Can I grow it in a container?: It can be grown in large containers with frequent watering and feeding but expect restricted growth and more frequent root pruning than in the ground.