A Leyland cypress can grow up to 3 feet in both width and height each year when it is young. Planting these evergreens too close together can stunt their growth and make them vulnerable to disease.
Leyland cypresses can grow up to 50 feet tall without pruning. They have a shallow root system and tend to topple if allowed to get too tall in wet soils. Topping the trees and trimming the side shoots can keep them at a more manageable size. Privacy can be maintained by planting the trees approximately 10 feet apart, giving room for lateral growth without interference. Careful spacing and pruning is necessary in order to grow an attractive hedge.