The Leyland cypress tree is a hybrid originated in England in 1888 from the cross between a Monterey and Alaska cedar. The species is an accidental occurrence in nature. The tree can withstand temperatures as low as 0 degrees Fahrenheit and adapts to various soil types. The problem arises with the spacing between trees when planted in groups such as windbreaks or privacy hedges; or as a farming operation when raised for resale such as Christmas trees.
Leyland cypress trees grow naturally to heights of 70 feet with a width of 20 feet. Planting the cypress in rows 6 feet apart requires stunting the height to 20 feet. The width will adjust itself for the spacing between trees. Planting with trees 6 feet apart allows the full growing potential of the individual trees.
Watch for problems as the lower limbs are starved for nutrients if the tree spacing is incorrect for the height of the tree. Trees spaced at 5 feet on center can grow to heights of 20 feet before becoming stressed. When the tree grows over 20 feet it will send moisture to the top of the tree and deprive the lower limbs. Topping the tree off at 20 feet allows the lower limbs to continue receiving moisture and nutrients. This is because in times of stress, such as droughts or during winter, the tree reserves moisture for the upper portion to continue growing.
Rule of Fours
Use the "rule of fours" to determine appropriate spacing between trees. This rule states that the target height should be no more than four times the distance between trunks. For trees on a 5-foot center the height would be 20 feet; trees spaced 8 feet apart can grow to 32 feet high before needing to be topped off. Allow the tree to grow up to 2 feet higher than needed to ensure proper height for the rule.
Proper spacing for Leyland cypress trees depends on the pattern used for the spacing. Use a zig-zag pattern for wide privacy screens and commercial growing operations. With this spacing the trees can be planted in two parallel rows using 8 feet centers on the trunk, but the trees will appear to be placed at 4 feet apart. This will ensure faster closure between trees, but the stress will remain low because there is more room between them using the rule of fours.
Initial spacing for Leyland cypress is important because of the rate of growth for these trees. Average growth is 3 to 4 feet per year until the trees mature to their natural height of 50 to 70 feet. Within the first five years these trees will reach the point of growth where stress can occur from improper spacing.