Whether they are trees or shrubs, I usually place my conifers in locations where pruning will not be necessary. Conifers are often slower growing and differ in their ability to regenerate after pruning. Some, such as yews, will sprout new growth near the pruning site. Many others, such as pines, arborvitaes, and junipers, lack dormant buds and won’t germinate new growth on old branches or if pruned back beyond the needles. Conifers should never be severely pruned.
General maintenance – Narrowleaf evergreens are plants that have needles, such as juniper, pine, cedar, spruce, and yew. Although some dwarf forms are available, most cultivars require some pruning to control size, shape, and density. Maintenance pruning should be done to enhance the natural shape of the plant. The timing of selective pruning is less critical for narrowleaf evergreens since they are normally grown for their foliage and not for their flowers. They can be pruned in the winter and used for holiday decorations or pruned in early spring before new growth starts. A second light pruning (thinning and heading) is often done in late June to early July after new growth is completed. Long out-of-scale branches should be cut to a lateral or just above a vigorous side shoot on two- or three-year-old wood. Start at the top of the plant and work down, removing branches that extend out and over lower, shorter branches. Do not cut all branches back to the same length, or the natural shape of the plant will be lost. Make pruning cuts so they will be hidden by an overlapping branch.
Many conifers, such as arborvitae, develop an area on the inside of the plant canopy that has little or no foliage. Green foliage should remain on branches that are cut back. Avoid cutting back to bare branches — they seldom are able to develop new growth. Yews are the easiest conifer to prune. New growth will occur wherever cuts are made.
Pines are Unique – buds for new growth occur only on branch terminals. Pruning should be back to a branch or to the main trunk. An exception to this rule is in the spring when new shoots, which look like candles, develop. When the “candle” has extended about to its full length and the needles are still soft, remove about one-half the length of the candle.
Severe Pruning – Narrowleaf evergreens are less tolerant of severe pruning than broadleaf evergreens. Most narrowleaf evergreens do not have dormant buds on old wood. Heavy pruning can kill most narrowleaf evergreens. If narrowleaf plants become too large for their location, it’s best to remove them and replant them.
