Evergreens provide year-round greenery and beauty to your yard, as long as they are maintained. Failing to trim the trees can result in dangerous dead wood, while also increasing the chances of disease and pests.
1) Know the Pruning Zone
When trimming an evergreen, make all cuts in the area with active needle growth. This means you do not want to make a cut between the first set of needles and the trunk. This area is considered woody, which means it can put on no new growth. If you cut into the woody area, needles won't grow back and you will have a dead branch stub poking out of the tree.
2) Work With the Natural Form
Most evergreens come in one of two forms, pyramidal or rounded. Pyramidal evergreens have a shape reminiscent of the average Christmas tree. These trees should only be pruned lightly to remove damage and to maintain their natural shape. Rounded evergreens are often pruned into formal or informal hedges. The tops should never be pruned completely flat, though, as snow and moisture weight on the flat surface can split open the tree.
3) Train a Leader
Pyramidal evergreen forms have a central leader. Occasionally, growth pattern issues or damage can result in the leader forking or splitting into two. Two leaders weakens a tree and increases the chance of the trunk splitting in the future. Trim out the weaker of the two leaders. You can use a stake tied to the leader and trunk to help train the new leader to stay straight, just make sure to remove the ties by the next growing season.
4) Trim in the Right Season
Evergreen trees respond best when they are pruned during dormancy. Although the trees may stay green year-round, most enter dormancy and stop growing during the winter months. Late winter is the ideal pruning time since the wood has thawed but active new growth hasn't yet begun. You can do light trimming to remove damaged wood or to maintain the shape of rounded evergreens year-round, but save the major pruning for late winter.
5) Make the Right Cut
Large branches require special care so that they don't damage the tree when you remove them. First, cut a shallow notch in the branch about 2 inches out from the branch collar. Then, cut through the branch from the top 2 inches further in front of the first cut. The notch prevents the branch from breaking and tearing off the bark as you cut through it. Finally, make a third cut flush to the branch collar in order to encourage quick healing.
Contact a tree trimming service for more help with your evergreen tree care.