March kicks off the tree pruning season. When it comes to pruning conifers like spruce, pine and yew, March is a little early and here are important tips and rules to keep in mind.
As with any plant, pruning should only be done if there is good reason to prune. With landscape evergreens, there often isn’t a good reason. While rarely something we can do with shade trees, many evergreens can be planted and never pruned.
To avoid the need to prune an evergreen, keep mature size in mind when selecting and planting. Evergreen trees become quite wide at their base. Don’t assume a tree can be pruned to prevent it encroaching on sidewalks or driveways. Allow adequate space for it to grow.
Evergreens cannot be pruned back into wood that has no green foliage on the branch. New growth rarely occurs from bare branches. As evergreens grow in size, their center becomes devoid of needles due to shade. This limits how far back a conifer can be pruned and eventually it grows into sidewalks or driveways if not sited correctly. If pruned too far back, a bare spot is exposed that never fills in.
Evergreens are best not be sheared unless grown on a Christmas tree farm. If you want a formal evergreen hedge, Japanese Yews are the best choice. Yews have the ability to develop new growth on older wood if it is exposed to sunlight. While possible, it can take a number of years to fill in a bare area.
Another practice discouraged with evergreens is removing the lowest limbs. While this will not harm a conifer, it reduces the trees windbreak benefits and aesthetics.
If needed, the ideal time to prune conifers except pine is just before new growth begins in spring. With new growth typically starting in May, April a good time. Most evergreens have one growth spurt in spring. Japanese Yew have two growth spurts and if pruning to control height or a ragged appearance is needed, Yews are pruned again in July.
Avoid pruning evergreens after early August. This stimulates growth that would not harden off before winter and is damaged by cold temperatures or winter drying. Avoid pruning evergreens during winter as the cut ends can be damaged by cold temperatures.