Are Thuja invasive?

The genus Thuja includes several species commonly known as arborvitaes, which are often used as ornamental shrubs or trees in landscaping. While they are not generally considered highly invasive, their invasive potential can vary depending on the specific species and local conditions.

In some cases, certain species of Thuja can spread and become weedy if not properly managed. For example, the Eastern Arborvitae (Thuja occidentalis) is native to North America but can become invasive in some areas, particularly if it escapes cultivation and establishes itself in natural ecosystems.

It’s important to note that invasive potential can also be influenced by local climate, soil conditions, and the presence of other plant species. Before planting any species of Thuja, it’s advisable to check with local authorities or invasive plant databases to determine if it has a history of invasiveness in your region.

Are Thuja invasive?

In general, responsible gardening practices, such as choosing native or non-invasive species, and properly managing plants to prevent them from spreading beyond desired areas, can help minimize the risk of invasive behavior.

Is Thuja better than Leylandii?

The choice between Thuja (arborvitae) and Leylandii (Leyland cypress) depends on various factors such as your specific landscaping needs, climate, soil conditions, and preferences. Both Thuja and Leylandii have their own characteristics, advantages, and considerations.

Thuja (Arborvitae):

  1. Variety: There are several species of Thuja, such as Thuja occidentalis (Eastern Arborvitae) and Thuja plicata (Western Red Cedar), each with different cultivars. They come in various sizes, shapes, and colors, providing options for different landscape preferences.
  2. Appearance: Thuja is known for its dense, evergreen foliage, which can create a good privacy screen. They are often used as hedges or standalone ornamental trees.
  3. Hardiness: Thuja is generally hardy and can adapt to different soil conditions. They are suitable for a range of climates.
  4. Growth Rate: The growth rate can vary depending on the species and cultivar. Some Thuja varieties have moderate growth rates, while others may grow more slowly.

Leylandii (Leyland Cypress):

  1. Rapid Growth: Leylandii is known for its fast growth, making it an excellent choice if you’re looking to establish a privacy screen or windbreak quickly.
  2. Height: Leylandii can grow quite tall, providing effective screening for larger areas.
  3. Adaptability: It is adaptable to a variety of soil conditions but prefers well-draining soil. Leylandii is also generally hardy.
  4. Disease Concerns: Leylandii is susceptible to certain diseases, such as cypress canker, especially if not provided with proper care and spacing to promote good air circulation.


  1. Size and Space: Consider the available space and the desired height of the hedge or screen. Leylandii might be a better choice if you need a rapid solution for a larger space, while Thuja offers more variety in terms of sizes.
  2. Maintenance: Both Thuja and Leylandii require regular maintenance, including pruning. Leylandii may need more frequent trimming due to its rapid growth.
  3. Disease Resistance: If disease resistance is a significant concern in your area, you might want to research the specific diseases that affect these plants and choose accordingly.

Ultimately, the “better” choice depends on your specific needs and preferences. Consulting with local gardening experts or nurseries can also provide valuable insights based on your local conditions.

What is the best Thuja for privacy?

Several Thuja species and cultivars are well-suited for creating privacy screens or hedges due to their dense foliage and upright growth habits. The best Thuja for privacy will depend on your specific requirements, such as the desired height, growth rate, and local climate. Here are a few Thuja varieties commonly used for privacy:

  1. Thuja occidentalis ‘Emerald Green’: This cultivar is a popular choice for privacy screens. It has a narrow, pyramidal shape, with vibrant green foliage that maintains its color throughout the year. ‘Emerald Green’ is known for its dense growth and moderate height, making it suitable for smaller spaces.
  2. Thuja plicata ‘Green Giant’: ‘Green Giant’ is a fast-growing Thuja cultivar that can reach impressive heights, making it ideal for quickly establishing a tall privacy screen. It has a conical shape and vibrant green foliage.
  3. Thuja occidentalis ‘Nigra’ (Dark American Arborvitae): This cultivar is valued for its dark green foliage and upright, columnar growth habit. It can be used effectively for creating a narrow, tall privacy screen.
  4. Thuja occidentalis ‘Techny’: ‘Techny’ is known for its dense and compact growth, making it a good choice for privacy screens. It has a pyramidal form and dark green foliage.
  5. Thuja occidentalis ‘Holmstrup’: This cultivar is more compact and slower-growing than some other arborvitaes, making it suitable for smaller spaces where a slower growth rate is preferred. It has a dense, pyramidal shape.
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When selecting a Thuja for privacy, consider factors such as the available space, desired height of the screen, growth rate, and local climate conditions. Additionally, proper planting, spacing, and maintenance will contribute to the success of your privacy screen. It’s often helpful to consult with local nurseries or gardening experts who can provide advice based on your specific location and requirements.

Why avoid Leyland cypress?

While Leyland cypress (× Cuprocyparis leylandii or simply Cupressocyparis leylandii) is a popular choice for creating fast-growing privacy screens and hedges, there are some reasons why individuals might choose to avoid or be cautious when planting Leyland cypress:

  1. Disease Susceptibility: Leyland cypress is susceptible to certain diseases, most notably cypress canker (Seiridium cardinale). This disease can lead to dieback, browning of foliage, and potential death of the plant. The susceptibility to disease can be a concern, especially in regions where these diseases are prevalent.
  2. Over-Planting Concerns: In some areas, Leyland cypress has been over-planted, leading to concerns about the development of diseases and pests. The close proximity of plants can contribute to the rapid spread of diseases.
  3. Rapid Growth: While the fast growth of Leyland cypress is often desirable for quickly establishing a privacy screen, it can become a drawback if not properly managed. Without regular pruning and maintenance, the rapid growth can lead to a plant that is challenging to control in terms of size.
  4. Size Control Challenges: Leyland cypress can grow to significant heights if not regularly pruned. This can become an issue if the trees outgrow the available space or if local regulations restrict the height of hedges.
  5. Root System: Leyland cypress has a shallow root system, which can lead to stability issues in extreme weather conditions. It’s essential to plant them in well-draining soil and provide proper support to prevent wind damage.
  6. Monoculture Concerns: Planting a large number of Leyland cypress trees in a single area can create a monoculture, making the entire population more susceptible to diseases or pests. Diversifying plantings can help mitigate these risks.

While Leyland cypress can be a suitable choice for certain applications, it’s essential for individuals to be aware of these potential issues and to carefully manage their Leyland cypress plantings to promote the health and longevity of the plants. Before choosing any plant for your landscape, it’s advisable to research local conditions, consider alternatives, and consult with local gardening experts or extension services for guidance.

Can I plant a Leyland cypress next to a fence?

Yes, you can plant a Leyland cypress (× Cuprocyparis leylandii) next to a fence, but there are several considerations you should keep in mind:

  1. Spacing: Leyland cypress can grow quite tall and wide, so it’s important to consider the mature size of the tree and provide enough space for it to grow without becoming crowded against the fence. Planting too close to the fence can lead to maintenance challenges and potential damage to the fence as the tree matures.
  2. Height and Width: Leyland cypress is known for its rapid growth, and it can reach significant heights. Some cultivars can grow more than 60 feet tall. Ensure that the mature height and width of the Leyland cypress you choose are suitable for the available space next to the fence.
  3. Sunlight: Leyland cypress generally prefers full sunlight. Ensure that the location next to the fence receives adequate sunlight for the healthy growth of the tree.
  4. Soil Drainage: Leyland cypress prefers well-draining soil. Make sure the soil around the fence area drains well to prevent waterlogged conditions.
  5. Maintenance: Leyland cypress requires regular maintenance, including pruning to control its size and shape. If you plant it next to a fence, you may need to prune it to prevent overgrowth and ensure it doesn’t interfere with the fence structure.
  6. Wind Exposure: Leyland cypress can be susceptible to wind damage, especially in areas with strong winds. Planting it next to a fence may provide some protection, but consider the overall wind exposure in your location.
  7. Consider Alternatives: Depending on your specific needs and space constraints, you may also want to consider alternative evergreen trees or shrubs that are more compact and suitable for planting next to a fence.
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Before planting Leyland cypress or any other tree next to a fence, it’s advisable to consult with local gardening experts or extension services to ensure that your chosen plant is suitable for your specific conditions and to receive guidance on proper planting and maintenance practices.

How close to a fence can you plant a Leyland cypress?

When planting Leyland cypress (× Cuprocyparis leylandii) near a fence, it’s crucial to consider the mature size of the tree and provide sufficient space to avoid potential issues as it grows. The exact distance will depend on the specific cultivar, soil conditions, and local climate. However, here are some general guidelines:

  1. Spacing from the Fence: It’s generally recommended to plant Leyland cypress at least 5 to 10 feet away from a fence. This allows room for the tree to reach its mature width without growing into or against the fence. Providing adequate space also makes it easier to maintain the tree and the fence separately.
  2. Mature Size Considerations: Leyland cypress has various cultivars, and their mature sizes can vary. Some can grow to be quite large, both in height and width. Before planting, research the specific cultivar you have or plan to get, and take its mature dimensions into account when determining the planting distance.
  3. Pruning and Maintenance: Regular pruning is essential to control the size of Leyland cypress and prevent it from encroaching on the fence. Plan to trim the tree as needed to maintain a suitable distance and shape. Pruning is typically done in late winter or early spring.
  4. Sunlight: Ensure that the location allows the Leyland cypress to receive adequate sunlight. While planting near a fence can provide some wind protection, it’s important to consider the sunlight requirements of the tree for healthy growth.
  5. Soil Conditions: Leyland cypress prefers well-draining soil. Make sure the soil around the fence area drains well to avoid waterlogged conditions.
  6. Local Regulations: Check with local authorities or homeowners’ associations for any regulations or guidelines regarding planting distances and landscaping near fences.

Can I plant a Leyland cypress close to my house?

Planting a Leyland cypress (× Cuprocyparis leylandii) close to a house is generally not recommended, especially if it’s too close to the foundation. While Leyland cypress is often chosen for its fast growth and ability to create a dense screen for privacy, there are several considerations to keep in mind:

  1. Mature Size: Leyland cypress can grow to be quite large, both in height and width. Some cultivars can reach over 60 feet in height. Planting it too close to a house can result in the tree outgrowing the available space and potentially causing issues with the structure.
  2. Foundation and Structure Concerns: The roots of Leyland cypress are generally not overly invasive, but the size of the tree can become a concern. Planting it too close to the house may lead to issues with the foundation, as the roots may spread out and compete for space.
  3. Sunlight and Air Circulation: Leyland cypress requires full sunlight for optimal growth. Planting it too close to the house may result in shade that can impact the health of the tree. Additionally, good air circulation around the tree is essential to prevent potential issues such as diseases.
  4. Maintenance Challenges: Regular pruning is necessary to control the size and shape of Leyland cypress. If planted too close to a house, maintenance can become challenging, and the tree may become difficult to manage.
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As a general guideline, it’s recommended to plant Leyland cypress at a distance from structures that is equal to or greater than its mature width. This allows the tree to reach its full size without causing issues.

Before planting any tree close to a house, it’s advisable to consult with local gardening experts or arborists who can provide specific recommendations based on your local climate, soil conditions, and the layout of your property. Planting decisions should also adhere to any local regulations or guidelines regarding tree placement near structures.

Can leylandii roots damage house foundations?

Leyland cypress (× Cuprocyparis leylandii) is generally not known for having invasive roots that cause significant damage to house foundations. However, there are a few considerations to keep in mind:

  1. Root System: Leyland cypress has a relatively shallow root system, and the roots are typically not overly aggressive or invasive. While they may spread out, they are not likely to cause damage to foundations under normal conditions.
  2. Soil Conditions: Planting Leyland cypress in well-draining soil is important. Poorly drained or waterlogged soil can lead to root issues and may indirectly affect the health of the tree.
  3. Proximity to Structures: While Leyland cypress roots are generally not a major threat to foundations, it’s still recommended to plant them at a reasonable distance from structures, including houses. This helps prevent any potential issues as the tree matures.

What is the lifespan of a Leyland cypress?

  1. Lifespan: Leyland cypress is a relatively fast-growing tree, and its lifespan can vary. On average, they may live for 20 to 25 years or more under favorable conditions. However, factors such as climate, soil quality, disease resistance, and overall care can influence the tree’s longevity.
  2. Disease Susceptibility: Leyland cypress is susceptible to certain diseases, such as cypress canker, which can impact its health and lifespan. Proper care, including pruning, maintaining good soil drainage, and addressing any signs of disease promptly, can contribute to a healthier and longer life for the tree.

In summary, while Leyland cypress is not typically associated with aggressive or invasive roots that damage foundations, it’s important to plant them at a reasonable distance from structures. Additionally, providing proper care and monitoring for signs of disease can help ensure the health and longevity of Leyland cypress trees in your landscape.



  • James Jones

    Meet James Jones, a passionate gardening writer whose words bloom with the wisdom of an experienced horticulturist. With a deep-rooted love for all things green, James has dedicated his life to sharing the art and science of gardening with the world. James's words have found their way into countless publications, and his gardening insights have inspired a new generation of green thumbs. His commitment to sustainability and environmental stewardship shines through in every article he crafts.

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