Leyland cypress (× Cuprocyparis leylandii) is a fertile hybrid cross between Monterey cypress (Cupressus macrocarpa) and nootka false cypress (Chamaecyparis nootkatensis). It is a fast-growing evergreen conifer (18 to 36 inches per year in early years) with a dense, broad-columnar to narrow-pyramidal habit. It typically grows as a tree to 60 to 70 feet tall unless it is kept pruned as a hedge or specimen shrub. From its nootka false cypress parent, it inherits its habit, foliage, and winter hardiness, and from its Monterey cypress parent, it inherits its branching pattern and rapid growth. Leyland cypress has flattened sprays of gray-green foliage on slender upright branches, and dark brown fruiting cones, 3/4 inch across with eight scales. The scaly bark is reddish-brown.
Leyland cypress trees will give you fast growth if you are looking for a privacy screen or a Christmas tree for your yard. For best results, plant the trees when they are dormant in the fall, about six weeks before the first frost. They are tolerant of pruning, but be prepared to prune often if you want to maintain a certain size or shape.
|Botanical Name||× Cuprocyparis leylandii|
|Common Name||Leyland Cypress|
|Plant Type||Coniferous evergreen tree|
|Mature Size||60 to 70 feet; 10- to 15-foot spread|
|Sun Exposure||Full sun to part shade|
|Soil Type||Fertile, moist, well-drained soil|
|Soil pH||5.0 to 8.0 (acidic to slightly alkaline)|
|Hardiness Zone||6 to 10 (USDA)|
|Native Area||Cultivated hybrid; parents are North American natives|
|Toxicity||Possibly to dogs and horses if ingested|
Leyland Cypress Tree Care
Leyland cypress trees are generally grown to meet an urgent need for a mass of evergreen foliage to create a privacy hedge. Height can vary greatly, depending on the variety and the conditions in which you grow them. For best growth, plant in a full sun site with evenly moist fertilized soil. The average height for an untrimmed Leyland cypress is about 50 feet, but do not be surprised if yours grows much higher or much shorter than that. Taller than they are wide, the spread of this columnar tree is commonly only one-third or one-fourth of the height, sometimes less.
A common landscape use is planting several Leyland cypresses along a border, in order to create a privacy screen. They are also used as windbreak trees. Since they are amenable to shearing or pruning, some homeowners take this a step further and turn such a border planting into a formal hedge.
Be sure to prune them early and often; otherwise, due to their fast growth rate, they tend to get too tall too quickly and can overwhelm a landscape. In addition to these practical landscaping uses, these plants are frequently used as Christmas trees.
While Leyland cypress is forgiving of most light conditions, it does not tolerate shade well. It grows best in open, sunny conditions or partially shaded areas.
Although it prefers a moist, fertile, well-drained soil, this tree tolerates a wide range of soil types—clay, loam, or sand and acidic or alkaline.
The tree tolerates occasional drought or brief waterlogging. To help its roots get established after spring or summer planting, water your Leyland cypress regularly. A Leyland cypress will take a few months to get established. After that, apply one gallon a week to the rootball if you live in USDA zones 7 or 8, and two gallons a week if you live in USDA zones 9 or 10. For the first and second years, water your Leyland cypress twice a week through spring and weekly in summer, tapering off to once to twice a month in winter. The older the tree, the longer you can go between waterings. Use soaker hoses, not sprinklers that will wet the foliage.
Temperature and Humidity
Leyland cypress trees are best grown in USDA hardiness zones 6 to 10, with temperatures no lower than -8 degrees Fahrenheit. However, zone-5 gardeners have been successfully growing them by providing mulch and an A-frame shelter in the winter months to protect them from snow and ice damage. Such sheltering is feasible only while the plants are young—unless you keep them short by pruning. Luckily, once the plants have matured, sheltering becomes unnecessary, as they will prove to be sufficiently cold-hardy in zone 5.
Fertilize Leyland cypress in early spring, before new growth begins. Spread a general-purpose, 10-10-10 fertilizer around the tree's drip line.
Is Leyland Cypress Toxic?
The sap of the tree can cause skin irritation to humans. The leaves if eaten are poisonous to grazing animals like horses or pets such as dogs.
Symptoms of Poisoning
Some individuals might experience skin irritation if they come into contact with the sap of Leyland cypress. It's not life-threatening and can be treated with simple over-the-counter ointments.
Consumption of the leaves is dangerous for anyone, although the chances of a human eating leaves are rare. If consumed, symptoms include weakness, loss of appetite, and diarrhea. If any part of the plant is ingested by an animal, take it to the vet immediately.
Leyland Cypress Varieties
There are many cultivars of Leyland cypress that are identified by the color of their foliage:
- 'Leighton Green' is commonly used as Christmas trees. Its dark, forest-green foliage makes it ideal for holiday decorating. Heavy and stout, this cultivar has a coarser appearance than other varieties.
- 'Silver Dust' has a leaf structure similar to 'Leighton Green' but with white variegated splotches on the foliage.
- 'Naylor's Blue' is known for its attractive blue-gray foliage. It grows to up to 60 feet tall and 10 to 15 feet wide. The scaled needles vary in color depending on the season. In winter it takes on a ghostly grey hue.
- 'Castlewellan' tends to grow in a conical shape. Its delicate, lacy foliage is a favorite feature. In the winter, the tree's exterior turns a gold hue while the interior remains green.
Pruning Leyland Cypress
The height of a Leyland cypress can be controlled (you can grow them as multi-stemmed shrubs), but only through persistent pruning that starts when the plants are young. Trim the sides of Leyland cypress trees every year in July. After the leader has reached the height you want the tree to retain, make a pruning cut a few inches below that (which will leave room for the vertical growth of minor branches) to preclude any further significant upward growth, as you would do when pollarding a tree.
Propagating Leyland Cypress
Since the tree is a hybrid, the Leyland cypress is almost always sterile and propagated mainly from cuttings. Successful rooting is achieved most often with cuttings taken from trees less than 10 years old, or from new shoot growth on older trees. January, February, or March are the best months to do the cutting. Cuttings should be 6 to 8 inches long and show some brown coloration in the lower part of the stem.
Dip the end of the stem in a rooting hormone used for woody trees. Plant into a porous planting media. Maintain the cutting in a warm, humid environment. Once the plant develops roots, transplant into a gallon-sized container. After six to nine months, the plant should be ready for planting outside in the spring.
Leyland cypress trees are shallow-rooted, meaning they can topple over easily, and they are susceptible to canker, which are dead sections caused by fungus or bacteria. If a canker appears, destroy any diseased areas. Clean any pruning tools between each cut to keep the disease from spreading.
You may also experience infestations of spider mites on this tree. A natural solution for this problem is to spray with neem oil. Another pest that can attack the plant is bagworm; deal with these by picking off the "bags" as soon as you see them.