- Grow Leyland cypress in regions with cool to mild winters. Excessive winter cold, with temperatures below -15 degrees Fahrenheit, kills the trees. Most garden literature lists Leyland cypress hardy in U.S. Department of Agriculture plant zones 6 through 9, but it may survive in milder parts of zone 5b, especially in close proximity to the warming effects of the ocean. This evergreen also tolerates lots of summertime heat. It will grow in deserts as long as it does not dry out from winds or lack of irrigation. A warm summer promotes fastest growth.
- Leyland cypresses demonstrate limited ability to survive prolonged dry or soggy soils. They excel in fertile, moist but well-drained soils with occasional but short bouts of seasonal drought. Wet soils suffocate roots and encourage root rot, and dry soil can cause random branch dieback. Newly planted trees are most susceptible to drought because they have not yet established a wide-reaching root system. The trees tolerate clay, loam and organic matter-enriched sandy soils, but elevate plants on a berm in heavy soils to ensure adequate drainage.
- One of the most pervasive diseases on Leyland cypress trees in the United States is canker, caused most often by the fungal species Coryneum. The fungus seiridium also causes canker. Once infected, the tree's vascular system is disrupted and branches turn brown and die. Entire trees can die once weakened by infestations. Fungal spores and bodies in the soil can quickly infest nearby Leyland cypresses. Root rot and needle blights also occur and if severe enough can weaken plants and make them susceptible to environmental stresses or insects that collectively lead to death.
- Bark beetles, scale, caterpillar, sawfly and bagworms can invade Leyland cypress trees and cause a disruption in growth and plant vitality. Bagworms are particularly troublesome because the brown cocoons of the pest resemble the seed cones of the conifer tree. As the worms hatch each spring and summer, they suck juices from the plant, causing dieback. Any compilation of insect pests can weaken a Leyland cypress, causing dieback and loss of photosynthesis capabilities. Stressed trees succumb to dry or soggy soil, cold winters or fungal pathogens more readily.
- You can prune the leader shoots from the tops of Leyland cypress trees to limit the upward growth of the plants without harm. The frilly needle foliage also tolerates shearing well. However, if plants are staked and any rope or wire is left on trunks, the bark will grow over them so they can't be removed. As the tree enlarges, the rope or wire acts like a noose, cutting off the vascular tissues and cambium, thereby killing the tree above the constriction point. Removing bark, deliberately or from collective physical damage over time, in a complete ring around the trunk will also cause death of the tree above the damage ring.
Climate Considerations
Soil Insight
Disease
Insects
Physical Damage
SHARE
