Hornbeam hedges can rise as high as 9 m (30 feet), providing an ideal privacy or noise screen. They can also serve as a means of dividing property lines. Hornbeam hedges require trimming on occasion to maintain a clean and symmetrical appearance. Trimming also helps them retain their autumn leaves during winter.
Position a pair of stakes on all four sides of the hornbeam hedge, at the point where you want each side to end. The length of the stakes depends on the desired height of the hornbeam hedge. If the desired height of the hedge is 1.5 m (5 feet), use stakes longer than that. Use a hammer to drive in the stakes so that they settle firmly into the ground.
Tie a length of string to the base of one stake and wrap the string around the bases of the other three stakes. Hold a line level on the string to ensure the line is straight. Check for a level string line on all sides of the hedge.
Use a measuring tape to measure up the stakes to the desired height of the hedge. Tie a second string to the top of one stake at the desired height of the hornbeam hedge. Wrap the string around the tops of the other stakes. Check with your measuring tape to ensure the string is the same height from the ground on each stake. Also check each length of string with a line level to ensure it is straight.
Use hedge shears to cut off any branches above the top string lines to square off the hedge. Use the bottom line to trim around the base of the hedge. Use pruning shears to cut off the thicker branches. Trim as needed along the sides of the hornbeam hedge. Take a few steps back on occasion to check the hedge and ensure the cuts are even.
Remove the lines and stakes after you finish trimming. Repeat the trimming procedure as needed during the growing season.
Leave the base of the hornbeam hedge wider than the top when trimming to ensure the full hedge receives the proper amount of sunlight.
Always wear safety gloves when using hand tools to avoid injury.