Topiary is a type of shearing that shapes large shrubs into tall, round, pom-pom shapes. The topiary technique "originated in European formal gardens" and "requires the manipulation of the plant from an early age and the constant shearing of the plant to achieve the desired form," according to the University of Arkansas Cooperative Extension Service. Junipers, boxwood, yaupon hollies, yew and privet are the most common shrubs shaped into pom-poms with this shearing technique. The pom-poms look their best when kept pruned.
Remove all branches that appear diseased, damaged from a storm or a winter's freeze, ridden with insects, or dead. Use one-hand pruning shears to cut smaller branches and two-hand shears on thicker branches. This can be done any time of year.
Wait until midsummer to prune your pom-pom trees to regain their round shape. If more growth occurs, you can prune again in later summer.
Carefully study the pom-pom shape before you begin pruning. Look at it from the front, from behind and from both sides. Pay attention to branches that are too long or are hanging too low.
Twist garden wire into a circular shape just smaller than the pom-pom and place it over the shrub to help guide your pruning, if desired. This will help ensure you're left with a nearly perfect ball shape.
Remove branches that have grown too long beyond the pom-pom shape or are hanging too low past it. Also cut off sprouts.
Cut all twigs and remove all leaves along branches between pom-poms if multiple shrubs are planted next to each other or if more than one pom-pom has been sheared into one shrub. If you cut too much, don't worry -- it will grow back.
Annual pruning is just as important for optimal growth as water and fertiliser. Don't wait to prune pom-pom trees until they are bushy, too tall or grown beyond their round shape. It may be too late to reshape them. Branches thicker than 1/2 inch may require a saw or lopper. Pruning tools are best when kept sharp, clean and free of rust.
Make each cut back to or just above a growth point on the branch to ensure new growth from the area.