Arborvitae – The common name is latin for ‘tree of life’. Parts of the plant were once used for medicines. The genus Thuja includes two native species. Arborvitae are typically small to medium sized evergreens. Five species are generally used in cultivation from American and Eastern Asian species and their hybrids.
Arborvitaes are characterized by their dense pyramidal shape and fan-shaped flattened branches. The trees are commonly used as living fences and screens to block unwanted views and on property borders. The plants grow quickly and generally have few problems if cared for properly.
Sometimes arborvitae are used for hedges. In this case pruning should be done in late winter. The plan can be hard to distinguish from Chamaecyparis another common landscape conifer. Forestry uses of native species includes poles, siding and shingles.
Arborvitae are typically pest resistant. Diseases include leaf blight, juniper blight, tip blight, cankers; clean out interiors of cultivars due to dense branching capturing dead foliage creating rot. Insects pests include aphids, mites, scale and bagworms.
Species
- Thuja occidentalis – White Cedar/Eastern Arborvitae – native from Canada to North Carolina. Cuttings taken November-March; ‘Emerald’ 10-15’, narrow, conical, cold hardy, dark green; used for screening and accents often corners.
- Thuja plicata – Western Arborvitae – Alaska to California to Montana – not common in the south, one of the parents of ‘Green Giant’.
- Thuja orientalis – native to Korea and northern China; ‘Aurea Nana’, dwarf, dense, globular;
- Thuja standashii x plicata – ‘Green Giant’ – Today this plant is a mainstay of the nursery trade. It has mostly replaced the Leyland cypress for use as living fences. It is a vigorous grower being 50’ tall by 15’ wide and pyramidal in shape. Grows 3-4’ per year. The plant requires adequate water so should be watered during droughts. Generally pest resistant but has developing problems including canker diseases during wet weather.
*New cultivar -
Thuja standashii x plicata ‘Junior Giant’ – 15-20’ tall slow growing cultivar that could be a good alternative to ‘Emerald’.