Crown Raising Trimming Techniques

Raising

• Crown raising techniques are included with other tree trimming techniques, such as crown thinning and crown reduction. Crown raising is a form of tree surgery completed to remove limbs from the lower area of a tree to stop the tree from becoming a blockage to lines of sight and access along streets and roadways, the U.S. Forestry Service reports. When completing a crown raising on a street or sidewalk, a municipal ordinance usually provides information on the required height above street level. To remain healthy, the crown of a tree should be around two-thirds of the height of the tree above the ground.

Trimming

• In order to remove branches from a tree to complete a crown raising, the gardener should prune the branches from the node of each tree limb. The node of a tree branch is the position on the branch where a new growth attaches to another tree branch. The gardener should complete the trimming in the spring before the branches forming at nodes become mature. The length of the tree branch between nodes is called an internode, according to the U.S. Forestry Service. During a crown raising, the gardener raises the head of a tree until he achieves the required clearance for pedestrians, vehicles, buildings and lines of sight. Crown raising reduces the need to remove a tree that blocks access or lines of sight.

Maturity

• The gardener should complete the pruning of a tree for crown raising purposes before the tree reaches full maturity to avoid the appearance of large wounds where established tree limbs are removed, the Help With Trees website reports. She should focus her removal of tree limbs on the lower branches, with some crown raising techniques leaving some lower tree limbs to avoid vandalism and sun scalding, according to the U.S. Forestry Service. She can select a small number of newly grown tree limbs as temporary branches positioned around 3 to 6 inches apart.

Annual

• In order to retain the shape and distance from the ground achieved through a crown raising, the gardener should trim the head of a tree and the temporary branches annually to retain the desired size of temporary limbs. As the temporary limbs reach large sizes, he should remove the limbs to avoid problems with the lines of sight and access.