Cultivating Arborvitae Varieties (Thuja) for Lush Landscaping
Thuja, commonly known as Arborvitae, is a genus of evergreen trees and shrubs in the cypress family (Cupressaceae), along with junipers, and redwoods. Known for their dense, scale-like foliage and conical to pyramidal growth habit, Arborvitae varieties are widely used in landscaping for their ornamental appeal and versatility. They range from towering trees to compact shrubs, fitting various garden designs.
Native: The genus Thuja comprises five species native to North America and East Asia. The most common species, Thuja occidentalis (Eastern Arborvitae), is native to northeastern America, while Thuja plicata (Western Red Cedar) is indigenous to the Pacific Northwest. Thuja orientalis (Oriental Arborvitae), as the name suggests, originates from Asia.
Growth Habit: Typically, Arborvitae plants exhibit a pyramidal or columnar growth habit. However, the shape can vary significantly among cultivars, ranging from narrow, upright forms to rounded, globe-like shapes.
Size: The size of Arborvitae plants varies widely. Some species, like Thuja plicata, can reach towering heights of over 200 feet (60 meters)in their native habitat, while dwarf cultivars may only grow a few feet tall and wide, suitable for small gardens and container planting.
Flowers and Blooming Season: Arborvitae produces small, inconspicuous flowers in spring. However, the flowers are often overlooked due to their small size and being overshadowed by the dense foliage.
Foliage: The foliage of Arborvitae is one of its most distinguishing features. The leaves are small, scale-like, and grow in dense, flat sprays. The color ranges from bright green to golden, depending on the species and cultivar.
Fruit: After flowering, Arborvitae produces small cones or seed heads. These cones are not typically a major ornamental feature but add to the tree’s natural interest.
Bark: The bark of Arborvitae trees is generally fibrous and reddish-brown, becoming more furrowed and textured with age.
Hardiness: Species of Arborvitae exhibit robust hardiness and adaptability across various climates. Most thrive in USDA zones 2 to 7, resilient to harsh winters and temperate summers. Oriental Arborvitae (Thuja orientalis), in contrast, is suited to milder climates and is hardy in USDA zones 6 to 9.
Uses: Arborvitae is extensively used in landscaping for privacy screens, hedges, windbreaks, and ornamental plantings. Dwarf varieties are popular in rock gardens, foundation plantings, and as specimen plants in mixed borders.
Wildlife: Thuja trees provide valuable habitat for wildlife. They offer shelter and nesting sites for birds, serve as a food source for some bird species, and their dense foliage offers protection and cover for small mammals and insects, enhancing biodiversity in gardens and forests.
Toxicity: Arborvitae is generally non-toxic to humans but can be mildly toxic to pets if ingested in large quantities.
Deer and Rabbit: Many Arborvitae species may suffer some damage from deer and rabbits, especially during harsh winters when food is scarce.
Invasiveness: Arborvitae is not considered invasive and typically remains within its planted area, making it a safe choice for controlled landscaping.
Hydrangea paniculata ‘Grandiflora’ and Thuja occidentalis ‘Rheingold’
| Hardiness |
2 - 9 |
|---|---|
| Plant Type | Shrubs, Trees |
| Plant Family | Cupressaceae |
| Genus | Thuja |
| Exposure | Full Sun, Partial Sun |
| Season of Interest | Spring (Early, Mid, Late), Summer (Early, Mid, Late), Fall, Winter |
| Height | 6" - 60' (15cm - 18.3m) |
| Spread | 10" - 2' (25cm - 60cm) |
| Maintenance | Low |
| Water Needs | Average |
| Soil Type | Chalk, Clay, Loam, Sand |
| Soil pH | Acid, Neutral, Alkaline |
| Soil Drainage | Moist but Well-Drained, Well-Drained |
| Characteristics | Showy, Fragrant |
| Native Plants | United States, New York, New Jersey, New Hampshire, Maine, Massachusetts, Maryland, Connecticut, Rhode Island, Pennsylvania, Vermont, Northeast, California, Rocky Mountains, Alaska, Midwest, Southeast, Pacific Northwest, Minnesota, Indiana, Illinois, Iowa, Michigan, Wisconsin, Ohio, Idaho, Oregon, Washington, Kentucky, West Virginia, Virginia, Tennessee, North Carolina, Montana |
| Attracts | Birds |
| Landscaping Ideas | Beds And Borders, Patio And Containers, Hedges And Screens |
| Garden Styles | City and Courtyard, Gravel and Rock Garden, Informal and Cottage |
Landscaping with Arborvitae trees and shrubs offers a combination of aesthetic appeal and practicality. These evergreen plants are versatile and can be used in various ways to enhance your outdoor space. Here’s how to effectively incorporate Arborvitae in your landscaping:
Creating Natural Borders: Arborvitae are excellent for forming natural borders along property lines or delineating different areas in your garden. Their dense foliage provides privacy and a lush green backdrop throughout the year.
Foundation Plantings: Planting Arborvitae around the foundation of your house can soften the architectural lines and integrate the building more naturally into the landscape. They can also help in insulating the house from wind and noise.
Windbreaks and Screens: In areas exposed to strong winds, rows of Arborvitae can act as windbreaks, protecting your garden and home. They are also ideal for creating privacy screens, blocking unwanted views and reducing noise.
Accentuating Paths and Driveways: You can plant Arborvitae along walkways and driveways to create a structured and elegant pathway. This adds a formal touch to the landscape.
Garden Focal Points: Specimen Arborvitae plants can be used as focal points in the garden. Their distinctive shapes and sizes can draw the eye and add interest to the landscape.
Mixed Shrub Borders: Combine Arborvitae with other shrubs and perennials for a varied and layered appearance. They provide a year-round green structure to the mixed border.
Container Planting: Smaller varieties of Arborvitae can be grown in large containers, making them suitable for patios, decks, and other areas where ground planting isn’t possible.
Wildlife Habitat: Arborvitae can provide shelter and nesting sites for birds. Planting them in your garden can encourage wildlife to visit.
Choosing companion plants for Arborvitae involves considering plants that complement its evergreen structure and can thrive in similar growing conditions. Here are some ideas for companion plants that pair well with Arborvitae:
Ornamental Grasses: Grasses like Hakone Grass or Blue Fescue can add texture and movement to the base of Arborvitae. Their fine foliage contrasts nicely with the dense Arborvitae leaves.
Flowering Shrubs: Shrubs like Hydrangeas, Rhododendrons and Azaleas, Dogwoods and Redbuds provide a burst of color and contrast well with the green backdrop of Arborvitae. They prefer similar acidic soil conditions.
Perennials: Hostas, with their broad leaves, offer a textural contrast and thrive in the dappled shade provided by Arborvitae. Other perennials like Ferns, Astilbe, Geraniums, or Hellebores can also be great choices for underplanting.
Bulbs: Spring bulbs like Daffodils, Tulips, or Crocuses can add seasonal color at the base of Arborvitae. They emerge and bloom before the trees leaf out fully, taking advantage of the light.
Growing and caring for Arborvitae (Thuja) is relatively straightforward, as they are hardy and low-maintenance plants. Here are some key guidelines to ensure your Arborvitae thrive:
Site Selection: Choose a location with full sun to partial shade. Full sun exposure leads to denser foliage growth. However, light afternoon shade is appreciated in hot summer climates. Arborvitae grows best in well-drained soil. Avoid areas that are consistently wet.
Soil Preparation: Arborvitae prefers slightly acidic to neutral soil. Amend the soil with compost or peat moss if necessary to improve drainage and nutrient content.
Spacing: Consider the mature size of your Arborvitae variety to determine spacing. Plant them far enough apart so they have room to grow, both in height and width.
Planting: Dig a hole as deep as the root ball and twice as wide. Place the plant in the hole, ensuring it’s level with the ground. Fill the hole with soil, gently tamp down, and water thoroughly.
Initial Watering: Water the plants deeply after planting. Keep the soil consistently moist but not waterlogged during the first growing season.
Ongoing Watering: Once the Arborvitae is well-established, make it a habit to check the soil regularly. When the top inch of soil becomes dry, it’s time to water the tree deeply. Focus on watering under the tree’s canopy, but maintain a distance of several inches from the trunk. This method conserves water and also reduces the risk of root rot.
The watering needs may increase for Arborvitae planted in containers, especially in hot and dry conditions. These may require watering as frequently as every day to maintain proper moisture levels.
When to Fertilize: Apply a balanced, slow-release fertilizer in early spring before new growth begins.
How to Fertilize: Follow the instructions on the fertilizer package for application rates. Avoid over-fertilizing, which can harm the plant.
Pruning Time: The best time to prune Arborvitae is in late winter or early spring, before new growth starts.
How to Prune: Prune to shape the plant or control its size. Avoid cutting into old wood, as Arborvitae do not regenerate well from old wood.
Benefits: Mulch helps retain soil moisture, regulates soil temperature, and suppresses weeds.
Application: Apply a 2-3 inch layer of organic mulch around the base of the plant, keeping it away from the trunk to prevent rot.
Protection: In areas with heavy snow, protect Arborvitae from breakage by wrapping them with burlap or tying the branches loosely.
Watering: Provide water during fall before the ground freezes, especially in dry weather, to prevent winter burn.
By following these care guidelines, your Arborvitae should grow healthy and strong, adding beauty and structure to your landscape for many years.
Arborvitae can be susceptible to certain pests and diseases. Here’s an overview of the most common issues that can affect Arborvitae:
Bagworms: These caterpillars create distinctive bag-like structures on the branches, feeding on the foliage. Heavy infestations can defoliate and weaken the trees.
Spider mites: These tiny pests are difficult to see but can cause the foliage to turn yellow or brown. A fine webbing on the tree is a telltale sign.
Scale insects: These small, immobile insects attach themselves to the stems and branches, sucking sap and weakening the tree. They often appear as small bumps on the tree.
Leafminers: The Arborvitae leafminer, a small moth larva, causes brown tips and foliage damage by tunneling into Arborvitae leaves, leading to defoliation and potential tree weakening if infestations are severe.
Cypress Tip Miner: This insect’s larvae burrow into the tips of branches, causing tip dieback. Infested tips may turn brown or gray and can be pruned out. Thuja plicata is resistant to infestation and Thuja occidentalis is highly susceptible.
Deer: While not pests in the traditional sense, deer can cause significant damage to Arborvitae by eating the foliage, especially in winter.
Root rot: Overwatering or poor drainage can lead to root rot, where the roots start to decay. Symptoms include yellowing or browning of leaves and dieback.
Needle Blight: This disease is typically caused by fungal pathogens ( such as Pestalotiopsis and Phyllosticta) and is characterized by the browning and eventual death of the needles.
Canker: Caused by fungi, cankers are sunken, diseased areas on branches or the trunk. They can girdle and kill branches or even the whole tree.
| Hardiness |
2 - 9 |
|---|---|
| Plant Type | Shrubs, Trees |
| Plant Family | Cupressaceae |
| Genus | Thuja |
| Exposure | Full Sun, Partial Sun |
| Season of Interest | Spring (Early, Mid, Late), Summer (Early, Mid, Late), Fall, Winter |
| Height | 6" - 60' (15cm - 18.3m) |
| Spread | 10" - 2' (25cm - 60cm) |
| Maintenance | Low |
| Water Needs | Average |
| Soil Type | Chalk, Clay, Loam, Sand |
| Soil pH | Acid, Neutral, Alkaline |
| Soil Drainage | Moist but Well-Drained, Well-Drained |
| Characteristics | Showy, Fragrant |
| Native Plants | United States, New York, New Jersey, New Hampshire, Maine, Massachusetts, Maryland, Connecticut, Rhode Island, Pennsylvania, Vermont, Northeast, California, Rocky Mountains, Alaska, Midwest, Southeast, Pacific Northwest, Minnesota, Indiana, Illinois, Iowa, Michigan, Wisconsin, Ohio, Idaho, Oregon, Washington, Kentucky, West Virginia, Virginia, Tennessee, North Carolina, Montana |
| Attracts | Birds |
| Landscaping Ideas | Beds And Borders, Patio And Containers, Hedges And Screens |
| Garden Styles | City and Courtyard, Gravel and Rock Garden, Informal and Cottage |
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Create a membership account to save your garden designs and to view them on any device.
Becoming a contributing member of Gardenia is easy and can be done in just a few minutes. If you provide us with your name, email address and the payment of a modest $25 annual membership fee, you will become a full member, enabling you to design and save up to 25 of your garden design ideas.
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