Fast growing Leyland cypress (Cupressocyparis leylandii) trees make an ideal privacy screen, since they grow quickly and never loses their leaves. This tree thrives in hardiness zones 6 to 10.
The amount of time it takes to grow your Leyland cypress 12 feet depends on the size you start with. These trees may be sold at a height of 1 to 2 feet, 2 to 4 feet, or 4 to 6 feet. If you're in a rush, pick the largest sapling to get off to a good start.
Leyland cypress trees grow as much as 4 feet per year when they are young. So a tree that's 4 feet tall when purchased could reach 12 feet within two years. A tree that's 2 feet tall at planting time will need at least 30 months to reach 12 feet in height.
Your Leyland cypress will keep growing once it reaches a height of 12 feet. If you want to maintain a smaller tree, you will need to prune it frequently.