Pruning is one of the most neglected aspects of tree care, and improper pruning can be very harmful to the tree. Cedar trees such as red or white cedar require very little pruning. Pruning should be done in late winter or early spring.
One of the first occasions for pruning a cedar tree occurs during planting time. Pruning a cedar during planting reduces the canopy so that the roots are not stressed. This gives the roots a chance to put their energy into developing a new, stronger root system rather than feeding branches in the tree. The small branches of a transplanted tree are also easier to manage while pruning. Small, light branches may be pruned with bypass pruners or small branch loppers at this stage.
This is also the time in which to shape the tree, since removing small branches will not change the overall appearance of a young tree too dramatically. Once a young tree is shaped, it should maintain that basic shape throughout its lifetime. Most cedars have a central trunk. Shaping should remove any developing second trunks as well as thinning branches that could grow to become too crowded on the tree. Additionally, any branches that fork from the primary branch at an angle less than 90 degrees should be removed. Branches that have weak forks will break easily.
Late winter or early spring is the best time for both transplanting and pruning trees. During this time, the sap in cedars is low and bark is not easily damaged. Pruning live branches in late spring and summer when sap has risen will attract insects, damage bark and may weaken the tree, putting it at risk for fungal infection.
Pruning may be done any time of the year to remove dead, diseased, damaged or broken limbs. Pruning of this sort should be done as soon after the damage is noticed as possible to halt the spread of damage. The pruning cuts should remove all of the undesirable wood back to the healthy, undamaged wood on the tree. Dead limbs may be identified due to their lack of green foliage. Additionally, one can remove a small section of bark with a pocket knife or screw driver. If the layer beneath the bark is dry, the branch is dead.