Expert: Jim Hyland - 2/25/2009

Question
When and how much can be pruned off of 10 year old leyland cypress trees?

Answer
With its rapid growth a Leyland cypress hedge can soon become overgrown if not maintained at the required height. Healthy plants will usually respond well to a reduction of up to one-third of the height. This is best carried out in April as the new growth is about to begin.

Taking too much off of the top can result in a bare, flat-topped hedge, or result in the death of older or less vigorous plants. If a reduction in the width is required care needs to be taken not to cut back into older leafless growths, as new growth will not appear from bare wood.

Step 1: Inspect your tree. Look for problems like cankers and dead or broken branches. You should also look for multiple leaders (large vertical stems that compete with the main stem).

Step 2: Cut dead branches back until you reach healthy branches.

Step 3: Make cuts outside the branch collar. The branch collar is that bulging part of the branch between the branch and the trunk of the tree.

Step 4: Angle your cuts from 45 to 60 degrees. Cut branches that are greater than one inch in diameter using the following 3-step process.

Step 5: Starting from the underside of the branch, measure 12 inches from the main trunk and make the initial cut about halfway through the limb.

Step 6: Make the next cut about one inch past the first cut and cut all the way through the limb, working from the top down. The weight of the limb should cause it to break between the two cuts.

Step 7: Make your final cut just outside the branch collar. There is no need to apply a wound dressing to the cut unless you’re controlling for insect diseases.

Step 8: Replace a damaged leader by training the uppermost lateral branch to grow vertically.

Step 9: Attach a long stick to the damaged leader with string. Bend the uppermost branch and tie it loosely to this stick.

Step 10: Prune any lateral branches beneath the new leader.

Maintaining a Leyland Cyprus is easy once you know the right way to prune.
Tips & Warnings
The best time to prune a Leyland Cyprus is from November through February.

When pruning diseased wood, disinfect your tools between each cut by wiping down the blades with rubbing alcohol.

A correctly trimmed tree adds to the real estate value of your property.

Avoid “topping” or drastically cutting off the top of a tree. Doing so decreases the tree’s ability to make food for itself.

Dull tool blades will crush, rather than cut tree stems.

Do not prune branches flush with the trunk.

Use a ladder and ask for help, when pruning larger trees.