The Leyland cypress (× Cupressocyparis leylandii) is a popular type of cypress within the cypress family (Cupressaceae). It is a hybrid species created by crossing the Monterey cypress (Cupressus macrocarpa) and the Alaskan cedar (Chamaecyparis nootkatensis). The tree was first cultivated in the mid-20th century and has since become widely planted for its rapid growth and attractive appearance. It is much used in horticulture, primarily for hedges and screens.
The genus is named after Christopher Leyland, on whose property in England two North American species of conifers, Monterey cypress (Hesperocyparis macrocarpa) and Nootka cypress (Callitropsis nootkatensis), accidentally cross-pollinated around 1888.
The Leyland cypress is fast-growing in nature. In the early years, it can grow up to 3 feet per year, and it has been known to reach 50 feet in height in 15 years.
Characteristics
- Generally, Leyland cypress trees have a columnar or pyramidal shape, with a dense and symmetrical crown.
- The foliage consists of feathery, scale-like leaves that are arranged in flattened sprays. The color is usually bright green, but it can vary depending on the specific cultivar.
- Mature trees can reach heights between 50 to 70 feet, with a spread of 15 to 25 feet. Large specimens tend to topple over.
- Cones are typically found at the tips of branches. They may be scattered throughout the tree, but they are not as noticeable as the foliage.In other words, they are small and inconspicuous compared to some other conifer species.
- Leyland cypress trees are adaptable to various soil types but prefer well-draining soil. They are tolerant of both acidic and alkaline soils.
- In the early years, the bark of Leyland cypress is smooth, thin, and reddish-brown to grayish-brown.
- As the tree matures, the bark becomes thicker and develops furrows, ridges, and a more fibrous texture.
- Branches are arranged in a horizontal to slightly ascending pattern.
- The tree is severely pest- and disease-prone and must be pruned regularly to maintain a tidy appearance.
- The Leyland is drought tolerant and hardy in Zones 6-10.
- It has a fibrous root system, consisting of numerous small, fine roots. The majority of the root system is concentrated in the top 12 to 24 inches of soil.
- While Leyland cypress has a relatively shallow root system, it forms a dense network that contributes to the stability of the tree.
- On average, Leyland cypress trees may live around 20 to 25 years, but some can persist for longer, potentially reaching 30 years or more.
Planting And Growing Conditions
- Choose a location that receives full sunlight for at least 6 to 8 hours a day. While Leyland cypress can tolerate partial shade, it thrives in sunny conditions.
- The tree prefers well-draining soil. Amend heavy or compacted soils with organic matter to improve drainage. Also the tree grows well in slightly acidic to neutral soil.
- Dig a hole that is as deep as the root ball and two to three times wider. This provides ample space for the roots to spread.
- Plant in the fall or early spring. This allows the tree to establish its root system before facing the stresses of summer or winter.
- Provide adequate spacing between trees to allow for proper growth and air circulation. The recommended spacing is typically around 5 to 10 feet.
- Water the tree thoroughly after planting to settle the soil and provide initial moisture for the roots.
- Consider light pruning at the time of planting to shape the tree and remove any damaged or dead branches.
- Monitor the tree regularly for signs of pests, diseases, or any issues with its overall health.
Uses of Leyland Cypress
| Landscape Use | Description |
|---|---|
| Privacy Screen | Leyland cypress is often used to create dense privacy screens and barriers due to its rapid growth and evergreen foliage, providing year-round visual screening. |
| Hedge Planting | The tree is popular for hedge planting, forming tall and dense hedges that act as effective windbreaks and provide a green, living boundary between properties. |
| Windbreaks | With its tolerance to wind and ability to form a dense canopy, Leyland cypress is suitable for planting as a windbreak, offering protection to landscapes and structures. |
| Ornamental Specimen | Planted as individual specimens in larger yards or landscapes, Leyland cypress adds an ornamental touch with its pyramidal shape and vibrant, feathery green foliage. |
| Screen for Undesirable Views | Strategically planted Leyland cypress trees can block or screen undesirable views, such as neighboring structures or unattractive landscapes, enhancing visual aesthetics. |
| Erosion Control | Planted on slopes or areas prone to erosion, Leyland cypress helps control soil erosion with its extensive root system, stabilizing the soil and preventing runoff. |
Common Diseases And Pests
Pests
Seiridium Canker (Cypress Canker)
Seiridium canker is a fungal disease that affects Leyland cypress, causing branch dieback, resinous lesions, and ultimately leading to the death of infected branches. The foliage may turn brown, and cankers often exude resin.
Pruning infected branches and promoting good air circulation can help manage the disease. Fungicides may be used preventively, and it’s essential to avoid stress factors that weaken the tree, making it more susceptible to infection.
Bagworms (Thyridopteryx ephemeraeformis)
Bagworms are caterpillars that construct protective bags from plant material and silk. They feed on Leyland cypress foliage, causing brown patches and defoliation. In severe cases, heavy infestations can lead to significant damage.
Handpicking bags from the tree and destroying them is an effective control method. Insecticides, applied at the right time in the bagworm lifecycle, can also help manage infestations.
Spider Mites
Spider mites are tiny arachnids that feed on the undersides of Leyland cypress needles. Infestations can lead to stippling, discoloration, and fine webbing on the foliage. Heavy infestations can cause significant stress to the tree, resulting in bronzing or browning of the needles and overall decline in health. Frequent washing of the foliage with a strong stream of water helps reduce mite populations. Insecticidal soaps or horticultural oils can be used,
Leyland Cypress Aphid (Cinara cupressi)
Leyland cypress aphids are small, soft-bodied insects that feed on the sap of Leyland cypress needles. They can be found clustered on the needles. Aphids cause needle distortion, yellowing, and stunted growth. The honeydew they excrete can attract sooty mold.
Insecticidal soaps or neem oil are effective chemical control options. Pruning and removing heavily infested branches can also be part of an integrated pest management strategy.
Diseases
Seiridium Canker (Cypress Canker)
Seiridium canker is caused by the fungus Seiridium unicorne. The disease typically manifests as resin-soaked lesions on the branches. Infected branches may display dieback, turning brown and eventually leading to the death of portions of the tree. The cankers may be visible as dark streaks on the affected branches.
Root Rot (Phytophthora spp.)
Various species of the genus Phytophthora can cause root rot in Leyland cypress. Root rot affects the root system, leading to symptoms such as wilting, yellowing of foliage, and general decline. In advanced stages, the bark near the base may exhibit cankers, and the tree may eventually topple.
Botryosphaeria Canker
Several species of fungi in the Botryosphaeria genus can cause cankers in Leyland cypress. Botryosphaeria cankers typically appear as sunken, discolored lesions on branches. The affected branches may experience dieback, and cankers may exude resin. Stress factors, such as drought or injuries, can increase susceptibility.
Needle Blight (Seridium spp. and Cercospora spp.)
Needle blights in Leyland cypress can be caused by various fungi, including species of Seridium and Cercospora. Needle blights result in the browning and dieback of needles. Infected needles may display discoloration, spotting, or lesions. Severe infections can lead to defoliation and overall tree decline.
What are the different Cultivars of Leyland Cypress
| Cultivar Name | Scientific Name | Appearance |
|---|---|---|
| Leylandii ‘Castlewellan Gold’ | x Cupressocyparis leylandii ‘Castlewellan Gold’ | Golden-yellow foliage, compact and columnar growth |
| Leylandii ‘Gold Rider’ | x Cupressocyparis leylandii ‘Gold Rider’ | Golden-yellow foliage, narrow and upright habit |
| Leylandii ‘Silver Dust’ | x Cupressocyparis leylandii ‘Silver Dust’ | Silvery-blue foliage, compact and pyramidal shape |
| Leylandii ‘Stapehill’ | x Cupressocyparis leylandii ‘Stapehill’ | Dark green foliage, dense and conical form |
| Leylandii ‘Leighton Green’ | x Cupressocyparis leylandii ‘Leighton Green’ | Bright green foliage, fast-growing and dense |
| Leylandii ‘Emerald Isle’ | x Cupressocyparis leylandii ‘Emerald Isle’ | Vibrant green foliage, compact and narrow habit |
| Leylandii ‘Silver Shadow’ | x Cupressocyparis leylandii ‘Silver Shadow’ | Silver-blue foliage, dense and pyramidal shape |
| Leylandii ‘Naylor’s Blue’ | x Cupressocyparis leylandii ‘Naylor’s Blue’ | Intense blue-green foliage, compact and upright |