Cupressus x leylandii
If there is one tree that has dominated screening and hedging plants for decades, it is the Leyland Cypress. When it was introduced to gardener’s in the 1960s, it became the ‘go-to’ plant for hedges and screening, and it was widely planted. Although today it has alternatives, such as Thuja Green Giant, it remains an outstanding choice when speed, vigor and size are the important features you are looking for in evergreens.
This evergreen tree forms a tall, flame-shaped upright plant, reaching 30 feet within 10 years, and eventually growing taller, with heights of 80 to 100 feet being recorded. It has a spread of 12 feet, and as much as 20 feet in time, although if trimmed regularly it can be kept as narrow as 3 feet for many years. The growth is naturally dense, and unclipped trees remain bushy and full almost to the ground. Since most plants are grown as hedges, and regularly trimmed, large trees are not seen too often. If trimming the top of hedges is not done, they will soon become very tall, with the potential to block light and views.
Leyland Cypress is one of the fastest growing evergreens there is. Young trees will easily grow 2 feet a year, even under poor conditions, and growth rates of 3 feet a year are common. If well-watered and intensively fertilized, 4 to 5 feet a year is not impossible in warmer climates.
Leyland Cypress has a strong central trunk, often dividing into two or more upright stems higher up the tree. The bark is rough and fibrous, gray-brown, and somewhat peeling. Since foliage is kept close to the ground for many years, the branches and trunk are not conspicuous.
The leaves of this tree are very small, about one-fifth on an inch long, and they cling tightly to the young stems, like the scales of a snake. The smaller branches are arranged in divided sprays, called branchlets, and these clusters make up the green foliage. They live for 3 to 5 years, before turning brown and falling to the ground, usually in early summer. The foliage is a rich green, with good color all year round, although some browning can occur in colder areas during winter.
The Leyland Cypress is a hybrid tree that does not produce cones, so it cannot be grown from seed.
Although the Leyland Cypress does not produce seeds, it can change. In the beginning there were six trees grown, each with slightly different characteristics. When available these are called ‘Haggerston 3’, ‘Haggerston 4’, etc. Another original tree is called ‘Leighton Green’. More importantly, the plant cells are not completely stable, and mutations, called ‘branch sports’, can occur. These have produced several valuable variations, and some of the most readily available ones are:
‘Gold Rider’ – With bright yellow new growth, turning lime-green as it matures, this colorful tree is smaller, and after a rapid period of growth when young it slows down when it is about 12 feet tall, and never passes 35 feet in height. With its bright coloring it is a good choice for a specimen, or a hedge, without the massive growth of the original tree. It is a branch sport of ‘Leighton Green’, found in 1986 at the Paul Vergeer Nursery in Boskoop, the Netherlands.
‘Moncal’ (Emerald Isle®) – this variation is more compact, with tighter branching, and it holds it color well through the winter months. It is good choice for smaller spaces, probably not exceeding 25 feet in height.
‘Murray’ – one issue with the Leyland Cypress is its susceptibility to disease when grown in the hot and humid south-eastern states. This form was found by Bill Murray, who had a Christmas tree farm in Georgia. It is very vigorous, disease resistant, and better adapted to both wet and dry conditions. There is a possibility that this plant is not a Leyland Cypress at all, but another hybrid, called Cupressus x ovensii, which involves the tough Mexican Cypress as a parent.
Uses in the Garden
Leyland Cypress can be grown as a single specimen tree, or a cluster of trees, but care should be taken in planting it with enough room for its large size, so that it doesn’t become a nuisance. Allow a minimum of 10 feet from walls, fences, and property boundaries, and 20 feet is a more desirable distance. Do not plant underneath or near overhead lines such as power or telephone. It is much more common to see this tree used as a hedging plant, and it is an excellent choice for larger properties where you have plenty of room available. For smaller gardens there are more compact choices available, including some of the special forms of this tree mentioned above, and further down.
The Leyland Cypress is very easy to grow, and it is often a good choice for city areas (where there is room) and along highways, because it has good resistance to air pollution. It is also resistant to salt spray, so it is a good choice for coastal areas, and close to the seashore.
This tree is recommended for taller screens and hedges. Hedges 6 feet tall or less are hard to maintain with such a vigorous plant, and alternatives should be planted. For larger screens and hedges, plant between 4 and 8 feet apart in a single row. If you have lots of room, and want a solid barrier, you can plant a double row, with the rows 3-5 feet apart and the plants 5 to 10 feet apart in the rows, staggering them in the spaces of the other row, like a zigzag.
Grow the Leyland Cypress in full sun for the best growth. It will grow in some shade, but the more shade, the thinner and weaker the growth, so always plant in as much sun as possible.
This tree grows in a wide range of soils, from sand to clay, and from dry to moist, but it performs best, and is healthiest, in moderately moist, well-drained soils. In wetter areas it can be planted on a mound of soil, and in sandy soils adding plenty of organic material to the soil will help retain water and nutrients.
Leyland Cypress grows best in soil that is not constantly dry, and, especially when newly planted, attention to watering during hot weather is important for health and good growth. Dry trees survive by stopping growing. Once well established it is drought resistant in ordinary summer dryness and needs little attention.
Winter hardiness and heat resistance
Zones 6 and 7 are the ideal growing areas for this tree. It is also hardy in sheltered parts of zone 5. It will grow in zones 8 and 9 too, but outside of the north-east often those areas are either very hot and humid, or very dry, and these conditions can cause problems. Some of the alternatives mentioned lower down may be better choices.
Pest and Diseases
Normally this tree is free of pests and diseases when grown in moderate climates, but the chances of disease are closely linked to high temperatures and high humidity. Some serious root diseases are seen in hot and humid states.
If the soil has been well-prepared, additional fertilizing is normally not necessary beyond the first few years, once the trees are well-established and their roots have spread widely.
Trimming and pruning
Plants for screens do not need trimming to stay dense, if you have room for their final height. Otherwise hedges and screens should be trimmed at least once a year, tapering the sides so that the top is narrower than the bottom. Trim from the beginning and remember that you cannot trim branches that have no leaves on them – bare limbs can never re-sprout. Spring and early fall are the best seasons for trimming.
Origin and History of Leyland Cypress Trees
Leyland Cypress is a hybrid between Nootka cypress (Cupressus nootkatensis) and Monterey cypress (Cupressus macrocarpa). Nootka cypress is a common forest tree in the Pacific northwest, while Monterey cypress is rare, today found in just a few spots along the coast of California. Both of these trees were growing in a garden in Wales in 1888, when Mr. John Naylor collected some cones from a Nootka cypress and a nearby Monterey cypress, and grew the seeds. His son inherited a grand estate, and he took six of the seedlings to the garden there. Called Haggerton Hall, he changed his own name to that of the original owner – Leyland. That of course is where the name of this plant comes from. It took a long time for anyone to pay attention to these trees, but eventually some gardening experts saw them, realized that they were hybrids, and slowly they were introduced to gardeners. The first were available in the 1920s, but it was only with the growth of suburbs in the 1950s and 60s that they really became well-known and widely planted. Plant breeders call the rapid growth and strength of plants like these ‘hybrid vigor’, where the plant is stronger than either parent.
Although the Leyland Cypress is a good choice for a lot of situations, there are other plants that can be better. Visit the entries on our site for more information on the following trees:
Thuja Green Giant (Thuja standishii x plicata) – a great replacement for the Leyland Cypress, growing smaller, but still large, very vigorous and quick growing, this hybrid has better disease resistance too.
Emerald Green Arborvitae (Thuja occidentalis ‘Smaragd’) – much more resistant to low winter temperatures, and slower growing, this plant is a good choice for smaller hedges.
Italian Cypress (Cupressus sempervirens) – this is the top choice for hot and dry climates, with great drought resistance, and dense, very dark green foliage.
Arizona Cypress (Cupressus arizonica) – a top choice for hot and humid or hot and dry areas, with very good resistance to diseases.
The Leyland Cypress is still an excellent choice for many situations, and highly recommended. Consider the space you have available, especially if it is not regularly trimmed, and if it is the best choice for your climate. If not, there are lots of good alternatives.