Weeping cherry trees originate from Japan and are among the more sought-after ornamental trees in Western gardens. They can grow as high as 40 feet, with a spread of 30 feet, with trailing branches similar to a weeping willow. In spring, they reveal blossoms of five or more petals ranging from snowy white or pale pink to deep magenta. These trees thrive in well-drained soils in gardening zones five through nine. To help enhance and maintain their unique appearance, careful trimming and pruning are necessary. Knowing how to properly trim a weeping cherry tree will allow you to enjoy its stunning beauty for many years to come.
Trim any upright vertical growths from the top of the tree, especially if the tree is very young. This will help to "train" the tree to continue to develop trailing branches. You may thin out the branches in the canopy to allow more sunlight, but always remove less than one-third of the total branches. Note that weeping cherries are grafted trees, but non-grafted trees should never be "topped."
Remove unwanted branches (or "suckers," as gardening professionals call them) as close as possible to the surface of the tree while they are still small. These usually appear beneath the grafted buds along the trunk about five feet off of the ground and must be removed to maintain the appearance of the tree.
Prune the trailing branches in a random, asymmetrical pattern along the perimeter of the canopy for the natural look that is preferred in Asia. Most Americans choose to keep the branches hanging no closer than 18 inches to the ground for aesthetic purposes.
Cut the trailing branches all to the same blunt length along the perimeter of the canopy for a more formally cultivated "umbrella" shape. This look, while less natural, appeals to many gardeners who prefer the classic lines of topiaries and geometrically trimmed boxwood hedges such as those found in the formal manor gardens of Europe.
Remove any dead, decayed or diseased wood that is present on the tree and carefully dispose of the fragments. Keep damaged and diseased cuttings out of your compost pile and away from the roots of other plants and trees. Apply a pruning sealant (found at your local plant nursery or garden supplier) to the cut areas of your tree for an extra measure of protection from pests and disease.
Prune a weeping cherry just after the blooms begin to fall away in the late spring. The blossoms normally will appear from early to mid-spring, and then give way to yellow-green leaf foliage in early summer.
Never prune a weeping cherry tree during the winter months. To do so will make the tree vulnerable to a botanical infection called silver leaf disease. Furthermore, if pruning is done in late summer, you will jeopardise future blossoms and growth.