Overview
The name “arborvitae” derives from Latin for “tree of life” and refers to several conifers of the cypress family native to North America and Asia. The two American species, the eastern and giant arborvitae, are, in their wild form, more commonly known as northern white cedar (Thuja occidentalis) and western red cedar (Thuja plicata), respectively. Both are popular landscaping shrubs and trees, often employed as dense-packed hedges or strikingly conical garden landmarks.
Common varieties of arborvitae grow as narrow pyramids, becoming tall, elegant, treelike shrubs that can reach a height of 40 to 50 feet in their native environment and 10 to 12 feet in urban settings. Their leaves have a scaly surface and are arranged into flattened sprays on the plant’s twigs, with leaves all in one plane. In spite of their scaly appearance, however, the leaves are quite soft when touched. Arborvitaes are commonly used as hedges or screens, although a few specimens make good accent plants in beds or borders.
Arborvitaes are monoecious, which means that the tiny pollen-bearing male cones and slightly larger seed-bearing female cones are produced on the same tree. Spring pollination is effected by the wind and results in the withering of the male cones and the early-fall ripening of the female cones, which turn from greenish yellow to brown, culminating in the release of small, winged seeds that are also dispersed by the wind.
Depending on the species and variety, arborvitae is relatively low maintenance. Arborvitae plants prefer fertile, well-drained yet moist soil of alkaline pH, although they are adaptable plants and can tolerate poor, rocky or sandy soil. They need full to partial sun and do poorly in full shade, becoming open and leggy without sufficient light.
Types And Cultivars of Arborvitaes
Types of Arborvitae
All arbovitae species are popular landscaping shrubs and trees, often employed as dense-packed hedges or strikingly conical garden landmarks. The five common species or types of arborvitae trees (Thuja) are:
- American arborvitae or Eastern arborvitae (Thuja occidentalis)
- Giant arborvitae (Thuja plicata)
- Korean arborvitae (Thuja koraiensis)
- Japanese arborvitae (Thuja standishii)
- Sichuan Arborvitae (Thuja sutchuenensis)
American Arbovitae
Thuja occidentalis, also known as northern white cedar, eastern white cedar, or American arborvitae is a small or medium-sized tree, growing to a height of 15-20 feet tall. The bark is red-brown, furrowed and peels in narrow, longitudinal strips. American arbovitae has fan-like branches and scaly leaves. The foliage forms in flat sprays with scale-like leaves which are usually lush light, medium or dark green, and with attractive cones.The plant typically maintain their foliage nearly all the way to the base of the trunk, giving the plants a formal, dense appearance.
Northern white cedar or tree of life, is a mainstay in the wild and in landscapes, hedges, windbreaks and outdoor containers throughout its hardiness zones. Easy to maintain and resistant to most pests and diseases.The trees are vulnerable to drought during their early years and prefer planting sites with full sun or partial shade and moist, well-drained, deep, calcareous or calcium-rich soils with a pH of 6.5 to 7.3.
Giant Arbovitae
Thuja giant (Thuja plicata), also known as western red cedar or giant arborvitae, is native to northern California, growing in both coastal and mountain areas. Thuja plicata leaves resemble scales, arising almost directly from the branches without discernible stems. Leaves are soft and usually a bright green, especially when newly opened. They have a pleasant but slightly medicinal aroma when bent or crushed.
Giant arborvitaes grow 50 to 70 feet tall and 10 to 15 feet wide, depending on the cultivar and growing conditions. It can reach several hundred feet in the wild. It’s shape is broadly conical toward the bottom and much narrower at the top, with shedding red bark, and small, half-inch cones.
Thuja giants are versatile landscaping plants. In large yards or rural areas, they can be used as a single specimen tree or planted in a row for an effective windbreak. Planting thuja plicata along a staggered border is one of the best ways to achieve a thick, lush screen. Giant thuja’s main problems are bark beetles, canker diseases and poor water management.
Korean arborvitae
Korean arborvitae (Thuja koraiensis) is a large, 15-17 feet-tall shrub with foliage that is made up of frond-like sprays that are sea-green or yellow-green in colour above and a silver-white underneath. This, along with a dark brown, peeling bark gives the Korean Cedar a striking appearance. The foliage is very aromatic and smells of almonds when crushed. Korean Cedar is extremely hardy and resists exposure well, as it grows naturally in the mountains of North-East Asia. You can plant them alongside walkways, patios and doors where brushing by them releases a fresh, cedarlike odor.
Korean arborvitae shrubs generally grow well in soil of any type, provided it’s well-drained. They develop their strongest color in full sun but can also tolerate partial shade for part of each day. In areas with strong, hot summer sun, providing some shade in the afternoon can help prevent scorching of the shrub’s leaves.
Korean arborvitae shrubs are generally disease-free plants. However, they are susceptible to bagworms, larval insects that hang from branches in their cone-shaped bags and feed on foliage and young branches.
Also Read: Types of Evergreen Trees
Japanese arborvitae
Thuja standishii (Japanese thuja) is native to southern Japan, where it occurs on the islands of Honshū and Shikoku. It is a medium-sized tree, reaching 20–35 m tall and with a trunk up to 1 m diameter. These evergreen plants have scalelike leaves and retain their branches clear to the ground even when mature, giving them good coverage as hedge plants.
The foliage forms in flat sprays with scale-like leaves 2–4 mm long, matte green above, and with narrow white stomatal bands below. Bark is reddish brown and fibrous. Sprays of foliage are flattened and rounded, with the ultimate branchlets alternately arranged.
Japanese arbovitae grow well in loamy soil but will tolerate clay and sandy soils, too. In very hot areas, the plants may need to receive some afternoon shade. Otherwise, they can grow in full sun to partial shade, in highly acidic to slightly alkaline soil.
Sichuan Arborvitae
Thuja sutchuenensis, the Sichuan thuja, is a species of Thuja, native to China, where it is an endangered local endemic in Chengkou County, on the southern slope of the Daba Mountains. It grows to heights of 30 to 65 feet tall with a trunk up to 1 foot (0.3 m) in diameter at breast height. The bark color ranges from bright reddish brown to grayish brown, furrowed, fibrous, and peeling in short, curly flakes. The crown is narrowly conical, with upwardly angled to horizontal branches bearing horizontal to slightly drooping branchlets.
Sichuan arborvitae is a fast growing, which is an advantage if you are trying to grow a privacy hedge or windbreak. Make sure you take into consideration the size of mature sichuan arborvitae before you plant to allow for enough space between plants at maturity.
Sichuan arborvitae are sturdy and require little pruning to maintain their naturally-occurring ornamental shapes, making them ideal for gardeners who want a low-maintenance evergreen. Even though they require little in the way of shaping care, yearly maintenance and pruning can keep your arborvitae looking its best. Prune or shape your arborvitae during spring, after the threat of frost has passed.
Cultivars of Arborvitaes
Arborvitae has more than 40 cultivars, including columnar, round and conical forms, and different height plants. Ordinarily slow-growing, some varieties of arborvitae are faster-growing. Although green is the most common foliage color, some arborvitae cultivars have foliage ranging from golden to copper. Once planted, arborvitae are low-maintenance shrubs but do require some care to stay healthy.
Pyramid Arborvitaes
Pyramidal Arborvitae is a fast-growing, tall, and narrow arborvitae pyramidal evergreen with bright green, soft-textured foliage. This tall arborvitae evergreen requires little or no trimming to maintain its narrow form.
This is a relatively low maintenance tree. When pruning is necessary, it is recommended to only trim back the new growth of the current season, other than to remove any dieback. It has no significant negative characteristics.
Pyramidal Arborvitae is recommended for the following landscape applications;
- Vertical Accent
- Hedges/Screening
Emerald Green Arborvitae
Emerald Green Arborvitae (Thuja occidentalis ‘Smaragd’) is a fuss-free tree. Growing in a sunny spot and average soil, this pyramid-shaped evergreen requires regular watering only to provide glossy-green foliage all year round.
Emerald Green Arborvitae grows best in well-drained, neutral or alkaline, moist loam soils and in spots that are sheltered from strong winds. For the densest foliage, grow the tree in a full-sun site and don’t allow the soil around a newly planted tree to dry out, or the leaves may drop. Emerald Green Arborvitae thrives in areas that experience regular rainfall. In hot climates, the tree benefits from light afternoon shade.
Hertz Wintergreen
Hetz Wintergreen Arborvitae is a multi-stemmed evergreen tree with a narrowly upright and columnar growth habit. Its average texture blends into the landscape, but can be balanced by one or two finer or coarser trees or shrubs for an effective composition.
This is a relatively low maintenance tree. When pruning is necessary, it is recommended to only trim back the new growth of the current season, other than to remove any dieback. It has no significant negative characteristics.
Hetz Wintergreen Arborvitae is recommended for the following landscape applications;
- Vertical Accent
- Hedges/Screening
Giant Green Arborvitae
Green Giant’ is a hybrid developed from a cross between the conifers Japanese arborvitae (Thuja standishii) and Western red cedar (Thuja plicata). Growing up to 4 feet yearly, it quickly develops into a mature tree, topping out at 60 feet tall and up to 30 feet wide. Dense, dark-green, open sprays of scale-like foliage form into a straight, pyramid-shaped form, changing to a slight bronze during winter and developing small, half-inch seed cones.
‘Green Giant’ is drought tolerant once established, but needs weekly water applications during its first year of growth and while it establishes itself. Though it tolerates drought, regular applications of water, especially during the hot summer months, promote the best growth.
Brandon Arborvitaes
Brandon Arborvitae is a dense multi-stemmed evergreen tree with a narrowly upright and columnar growth habit. Its relatively fine texture sets it apart from other landscape plants with less refined foliage.
This is a relatively low maintenance tree. When pruning is necessary, it is recommended to only trim back the new growth of the current season, other than to remove any dieback. It has no significant negative characteristics.
Brandon Arborvitae is recommended for the following landscape applications;
- Vertical Accent
- Hedges/Screening
Wareana Arborvitae
Wareana is a dense, pyramidal selection of arborvitae with stout ascending branches and thick, short, mostly vertically arranged compressed branchlets of coarse, dark-green foliage that does not tend to bronze in winter. After 10 years of growth, a mature specimen will measure 8 to 10 feet (2.5 – 3 m) tall and 6 to 8 feet (1.75 – 2.5 m) wide, an annual growth rate of 1 foot (30 cm) or less.
Techny Arbovitae
The Techny arborvitae is a cultivar of white cedar that was cultivated in Techny, Illinois. It is also called a mission arborvitae. Techny arborvitae are an evergreen that can grow to 15 feet tall and 8 feet wide. It can tolerate wetter locations, and should not be planted in extremely dry locations without frequent watering.Techny Arborvitae is great for creating a living fence and provides solid, year-round screening.
Techny’s compact, upright pyramidal shape provides an excellent accent or backdrop for other plantings, and you can easily prune it to your desired shape. The Techny Arborvitae is one of the most hardy of the Arborvitae, withstanding more cold and drought than other Arborvitaes. It can even live in a pot on your patio. No need for you to even mulch it as it drops its year’s previous growth in the fall.
Holmstrup Arborvitae
This densely branched, compact, naturally narrow and conical evergreen has a neat, formal appearance. It is slow-growing and will take 10 years to reach 10 feet tall and 2.5 feet wide. The foliage is attractive with scale-like leaves in dense horizontal sprays that hold their color well through winter. The form is a narrow pyramidal shape.
The dense form of this evergreen is impressive planted in a row along the edge of the garden or along the drive. It lends a formal look to the garden, and makes a good foil to shrubs with a more casual form. Planted singly, it makes a fine statement. It is also adaptable to various soil types but prefers moist well-drained loams. Use this tree in foundation plantings, as a hedge, or as a focal point in small gardens.
Little gem arbovitae
‘Little Gem’ is a dwarf Arborvitae cultivar that is dense, flattened, and broadly globular. It generally matures to only about 3′ tall and up to 6′ wide over the first 10 years. It holds its dark green color in winter although it sometimes turn to bronze-like Color. This plant is frequently damaged by deer.
Little Gem Arborvitae is recommended for the following landscape applications;
- Mass Planting
- Hedges/Screening
- Rock/Alpine Gardens
- General Garden Use
Woodwardii Globe Arborvitae
Woodwardii‘ arborvitae is a slow-growing, globose selection of Arborvitae that will become broadly rounded with age. It is distinctive though its upright branching that hold flattened sprays of medium green foliage. After 10 years of growth, a mature specimen will measure 3 to 4.5 feet tall and 3 to 4 feet wide, an annual growth rate of 4 to 6 inches.
Woodwardii Arborvitae is recommended for the following landscape applications;
- Mass Planting
- Hedges/Screening
- General Garden Use
Rheingold Arborvitae
Rheingold arborvitae is one of the most popular selections of Arborvitae in landscaping. It is distinctive when young through its dense globose form with coppery-yellow juvenile foliage. In summer, the color is more golden-yellow, while winter brings out the strong coppery overtones. Its best color develops when planted in full sun. Scale-like foliage appears in flat, fan-shaped clusters. As it matures it develops more scale-like foliage and a more upright conical form, reaching 6 feet tall and 4.5 feet wide in 10 years.
The shrub is adaptable to different soil types and acidity but prefers moist well-drained loams in sun to light shade with some protection from the wind. It may be used as a foundation plant, in borders, or mass plantings. Deer will browse this shrub.
Also Read: Difference Between Evergreen And Deciduous Trees
Hertz Midget Arborvitae
Hetz Midget’ Arborvitae is a dwarf evergreen plant. The form is more globose than conical, usually single trunked, and it slowly reaches 3-4 feet tall and slightly wider. The scale-like foliage is arranged in dense flat layered sprays. A very adaptable, tough, durable plant.
This bright small arborvitae is exceptional in limited city gardens and courtyards with trying conditions as small hedge or spherical semiformal accents. This form is exceptional for spare modern design gently clipped to geometric perfection. Use in beds and borders to add interest for the winter months, particularly under snow, when all else is bare. Adapts beautifully to wild and rock gardens where they are exceptional. A problem solver for formal gardens in dry climates of the Southwest where boxwood and other conifers suffer. Makes a fine container foliage plant for porch, patio and terrace.
Amber Gold Arborvitae
A striking upright evergreen shrub for home landscapes, maintains a dense, compact shape without pruning, features stunning yellow foliage that turns amber-gold in winter.This beautiful shrub does well in full sun, but will tolerate some light afternoon shade. Arborvitae requires deep watering in summer months and has medium watering requirements once established.
Variegated Silver Crested Arborvitae
Variegated silver crested arbovitae is a large, fast-growing, tree form of hiba arborvitae with species-typical form and branching, and attractive creamy white variegation that is fairly stable. The variegation and reduced chlorophyll results in slightly slower growth when compared with the species. After 10 years of growth, a mature specimen will measure 6 feet (2 m) tall and 4.5 feet (1.5 m) wide, an annual growth rate of 6 to 8 inches (15 – 20 cm).
Aurea Nana arbovitae
Aurea Nana’ has a similar growth habit to its relatives, conical and columnar, only on a smaller scale. Reaching only 2- to 5-feet in height and 2- to 4-feet in width, this attractive evergreen fits in perfectly in small urban spaces. The evergreen foliage of ‘Aurea Nana’ will have a bronze tinge during the winter months as a response to cold temperatures. This handsome shrub does well in full sun, but will tolerate some light afternoon shade. Arborvitae requires deep watering in summer months and has medium watering requirements once established.
Also Read: Types of Cypress Trees
Degroot’s Spire Arborvitae
Degroot’s Spire arbovitae is a beautiful dwarf evergreen shrub with twisted feathery sprays of rich green foliage that takes on a purple tinge during winter. It is reliable and cold weather resistant; and represent a hardy alternative to cypress. When you bruise the foliage, it gives off a very pleasant fragrance reminiscent of citrus.
Degroot’s Spire arbovitae produces a fine columnar form used in rows, pairs or as a single specimen. Perfect for an evergreen privacy screen or rich background for water features and art. Performs well in the wet, low lying areas of your garden or natural swamps and bogs. Place in paired containers as a formal statement to an entry or drive.
Golden Tuffet Arborvitae
Thuja occidentalis Golden Tuffet is a dwarf growing arborvitae with attractive yellow spring foliage, which matures to golden-orange with hints of lime green. It has a mounded form that is suitable for use as a foundation shrub and bed addition. Plant it in groups or as an accent plant. The plant is also hardy, durable and adaptable to all soil types and tolerates full sun to part shade.
Thuja plicata ‘Grune Kugel’
Grune Kugel is a dwarf globe shaped variety of Thuja plicata ( Western Red Cedar ). It is a slower growing variety, growing only a few inches per year. Foliage is typical of most Arborvitae varieties with a good green color year round with minor bronze colored tips in colder climates during the winter. Grune Kugel is a great choice for foreground or foundation plantings, and is very low maintenance with a globe shape as it matures.
Planting Arborvitae Tree
Choose a location in your yard that recieves 3 to 6 hours of direct sunlight per day with evenly moist soil. You need to amend your soil with some compost to further help your arborvitae tree to establish. When you are ready to plant dig a hole that is around twice a wide as the rootball and just as deep. Remove your plant from its container and gently place in the center of the hole backfilling to secure your plant in place. Mulch around your arbovitae making sure to leave a couple of inches between the start of the mulch and the base of your plant. This will reduce issues in the future. After planting water your plant deeply making sure the area surrounding the rootball is fully saturated.
Also Read: Different Types of Juniper Trees
Common Problems That Are Associated With Growing Arborvitaes
Arborvitae plants are susceptible to several insect pests, especially bagworms, the larvae of a common moth that build loose bags to cover their bodies, attaching the bags to arborvitae twigs. The larvae feed on the plant’s foliage through spring and summer, potentially doing serious harm. Bagworms can be hand-picked from smaller plants, and insecticidal sprays labeled for home use can be applied to larger plants.
Leaf miners and scale insects may also feed on arborvitae, but these can also be controlled with appropriate sprays. Deer may feed on arborvitae, especially on the lower branches, potentially interfering with the plant’s naturally symmetrical shape. In areas susceptible to cold winter weather, the plant’s flexible branches may be deformed by the weight of snow and ice.
Conclusion
Arborvitae has flat, scale-like foliage, which is usually a lush light, medium or dark green, and attractive cones. The plants typically maintain their foliage nearly all the way to the base of the trunk, giving the plants a formal, dense appearance.