How do I prune conifers?
Conifers do not in general need pruning and, in fact, prefer not to be pruned. Pruning should normally be confined to removing dead, damaged or diseased branches. In such a case, prune the branch down to live tissue or close to the tree trunk. If you do prune never remove more than a third of the live growth at a time.
Sometimes, however it is necessary to prune to reduce a tree's height, increase density of branching or to achieve a special shape. Different species require different pruning treatment according to their pattern of growth. Two types of branching patterns are found in conifers - whorled branches (pines, spruce, firs) or random-patterned branches (yews, arborvitae, hemlock, cedar and juniper).
These species generally have few buds or latent growing points on the branches, so the stems do not grow back when pruned.
Pines may be pruned by pinching candles (new growth) back by one half or a third. This should be done in the spring when the growth is fresh. Use your finger rather than a pruner. More extensive pruning can be done by removing whole branches rather than cutting back to old wood.
Spruce and Firs
To shape a tree, the new growth can be sheared in late spring. Branches can be pruned back safely to the nearest lateral branch or bud.
These species are much more tolerant of pruning as new branches develop from concealed buds in the crotches of the branches.
This species can be pruned quite heavily. To reduce the height of a shrub, cut it back to a lower branch crotch. In an older shrub with a dead internal part, do not cut back to dead wood.
Most junipers develop a dead zone in the center. Avoid pruning back into this area, otherwise branches can be cut back (about 20% at a time).
Yews are very tolerant of pruning as new growth will develop from old wood. Yews can be shaped by pruning through the spring and summer but do not prune in late summer or fall.
Hemlocks grow into large trees and should be allowed to grow into their natural shape if possible. If necessary branches can be cut back to new growth.
For a brief summary on pruning conifers consult the Morton Arboretum website.
For a more detailed discusson of pruning in general, and individual conifer species in particular, consult this book:
L Reich. The Pruning Book. The Tauton Press, Newtown CT. 1997.
Courtesy of NYBG Plant Information Service