Plant your Leyland cypress 12 to 15 feet apart, measured trunk to trunk. That Leyland cypress spacing is the minimum Clemson and UGA extension agents give you. It leaves each tree room to grow wide. It also lets the inside branches dry out fast after rain. When you are planting Leyland cypress for a screen, the urge is to set them tight for quick cover. Fight that urge, because the close row you plant today is the sick row you fight in three years.
The inner branches of my back-fence 'Leighton Green' row in Zone 7 Virginia turned brown two summers after I set them barely 6 feet apart. The needles dropped from the inside out and the whole screen went thin and patchy. I could see the fence through it by August. I pulled out every other tree that fall and braced for an ugly gap. By the next summer the spaces that were left filled back in solid green. Each tree could finally breathe and shed water off its foliage, and the brown never came back.
Here is the mechanism behind that recovery, and why your spacing choice is really a disease choice. When your trees sit too close, the inside branches stay damp for hours after every rain or heavy dew. That wet, trapped air is the whole problem. Needle blight and canker fungi love damp, still air, and a crowded row hands them the exact wet window they need. Space the row wide and air moves through it. The leaves dry within an hour or two, and the fungi never get their opening.
The number comes straight from how big this tree gets. A Leyland reaches up to 100 feet (30 m) tall and nearly 50 feet (15 m) wide in good conditions. Two trees set 6 feet apart are trying to share ground that one mature tree wants all to itself. Good cypress privacy screen spacing plans for the trunk you will have in 20 years. It does not plan for the skinny stick you carry home from the nursery. Picture the full-grown spread first, then set your stakes.
Distance from your buildings matters as much as the gap between trees. Keep the row well back from fences, walls, and driveways. A tree 50 feet wide will crowd a foundation or crack a driveway edge if you plant it too close to one. UGA agents warn about the damage a tree that size can do to a house only a few feet away. Give your row at least 10 to 15 feet of clearance from any hard structure, and more if you can spare the yard.
Already stuck with a crowded older row? You can still fix it without starting over. Pull out every other tree to open the line back up, the same move that saved my screen. The trees you keep look bare for a season, then spread to close the gaps with healthier growth. Wider spacing now beats a dead row in five years. So set your new trees at 12 to 15 feet, water them in, and let them grow into the room you gave them.
Read the full article: Cypress Trees: Types, Care, and Common Problems
