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Stark-Billings County |
Extension Spotlites
February 21, 2008
Help Trees Take Shape: Prune Properly
Why do people prune trees? People commonly prune trees to remove dead branches, remove crowded or rubbing limbs, or to eliminate hazards. Trees also are pruned to increase light and air penetration to the inside of the tree’s crown or to surrounding landscape. But in most cases, mature trees are pruned as a corrective or preventative measure.
Pruning techniques. There are specific types of pruning that help trees stay healthy, safe and beautiful.
Cleaning removes dead, dying, diseased, crowded, weakly attached, and low-vigor branches from the crown of a tree.
Thinning selectively removes branches to increase light penetration and air movement through the crown and reduces weight on heavy limbs to retain the tree’s natural shape.
Raising removes lower branches from a tree to clear space for buildings, vehicles, pedestrians and views.
Reduction trims the height or spread of a tree by pruning back the leaders and branch terminals to lateral branches that are large enough to assume the terminal role (at least one-third the diameter of the cut stem). Compared to topping, this helps maintain the form and structural integrity of the tree.
When to prune? This time of year– late winter and early spring–is the best time to prune most trees while they are still dormant. Note that there are three major exceptions: evergreens, flowering bushes and trees that bleed.
Proper pruning cuts. A pruning cut’s location is critical to a tree’s response in growth and wound closure. Pruning cuts should be made just outside the branch collar, which contains trunk or parent branch tissue that should not be damaged or removed. When removing a large limb, first reduce its weight to avoid tearing the bark. Make an undercut about 12-18 inches from the limb’s point of attachment. Then make a second cut from the top directly above or a few inches further out on the limb.
How much to prune. The amount to remove depends on the tree size, species and age as well as pruning objectives. Younger trees can tolerate more pruning than mature trees. A tree can recover faster from several small pruning wounds than from one large wound. Removing just one, large-diameter limb can create a wound that the tree may not be able to close. The older and larger the tree, the less energy it has to close wounds and ward off decay or insects.
Also see: Pruning Trees
For more information contact:
Kurt Froelich,
Extension Agent
NDSU Extension Service
Stark-Billings County
1340 W. Villard St.
Dickinson ND 58601-4646
(701) 456-7665