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Plant Care Resources

How to Prune Evergreen Trees and Shrubs

Prune with purpose and keep your evergreens healthy with expert guidance from The Morton Arboretum’s Plant Clinic.

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“Evergreens” refers to a group of plants that retain their foliage during winter. Pruning evergreens comes with specific needs and concerns.

Because evergreens maintain their needles all year, they tend to shade out their own interiors. That leads to two results. Many evergreens will become more open inside and new buds may not form on the interior branches. This lack of new bud formation produces an area referred to as the ‘dead zone’. This area is not really dead, but if pruning cuts are made into this area, there are no buds to sprout and fill in the gap produced by pruning. Whenever evergreens are being pruned, this area that lacks buds should be identified and avoided.

Shearing, rather than pruning evergreens, makes the outer layer of needles more dense. This shades the interior more and promotes faster development of the dead zone, making future pruning efforts more difficult.

Evergreens tend to go into dormancy more slowly than other plants, so late summer and fall pruning should be avoided to prevent stimulation of new growth at a time when the plant should be slowing down for the season.

The best time to prune evergreens—except pines—is before new growth starts in the spring.

When cutting larger branches with a pruning saw, use the three-step process.

Identifying Whorl-Branched or Random-Branched Evergreens

Proper identification and growth habits are necessary before pruning an evergreen to maintain the natural shape and beauty of the plant.

Evergreens can be grouped on the basis of whether they have whorled branches (pines, spruces, firs, and Douglas-fir) or random-branching patterns (yew, arborvitae, and juniper).

New growth is produced primarily from buds that were formed the previous year on the tips of twigs. However, a few random-branched species are capable of generating new growth on both old and new wood portions of the branch.

Whorl-Branched Evergreens

Pines, spruces, firs, and Douglas-firs

Random-Branched Evergreens

Arborvitae, junipers, and yews

When to Prune Evergreens

Prune all evergreens—except pine—before new growth starts in the spring. Remove dead, diseased, or broken branches anytime.

When pruning, follow the general branching pattern to maintain the natural shape.

In most cases, selective pruning (one branch at a time) is better than shearing. Shearing creates a formal, geometric shape that looks out of place in a natural landscape and becomes more difficult to maintain as the plant increases in size.

When shearing, begin in late spring when new growth begins. This allows cuts to heal and new buds to form for next year. Pruning paints or sealants are not necessary.

Occasionally, an evergreen may lose its leader, or topmost branch. Sometimes a new leader develops from a dormant side bud, or one of the uppermost branches will dominate and become the new leader. If no leader develops naturally, tie one of the topmost branches upright using a small piece of wood and soft ties that will not cut into the stem, training it to become the new leader. Remove the ties before the next growing season begins.

Whorl-Branched Evergreens

Pines (Pinus)

Pine trees need very little pruning. Branches that are dead or broken can be removed any time of the year. Most pines produce their buds on the terminal tips of their shoots and not along the stems. This results in one flush of growth per year. New shoots are called candles.

If needed, prune pines in the spring just as new growth emerges. To slow the growth of the pine, pinch one-third to one-half of each candle when it expands in the spring.

Do not prune back into woody stems; new growth will not develop from these areas. Shearing is not recommended.

Spruce (Picea), Fir (Abies), and Douglas-Fir (Pseudotsuga)

Spruce, fir, and douglas-fir trees also need very little in terms of pruning. Unlike pines, these species have buds scattered along the twigs of the newest growth, as well as at the terminal tips of the branches.

To maintain a good shape, prune new growth in the spring. To reduce the size of a branch, cut back to a small lateral branch or a visible dormant bud. This is best done in spring. It should be done in moderation and only if visible buds can be identified. Shearing is not recommended.

Although these species need very little pruning, bottom branches may die with age and can be removed at the trunk. Do not leave stubs.

Random-Branched Evergreens

Arborvitae (Thuja)

Arborvitae come in many different forms and sizes, but often need little pruning to maintain those forms.

Arborvitae are responsive to pruning because new branches develop from concealed buds in the branch crotches.

When needed to maintain shape, prune in spring around the time of new growth. When heavy pruning is necessary, prune before new growth begins in early spring so that new growth conceals pruning cuts.

Older arborvitae growing in shade will develop a more open form and larger dead zone that is incapable of regenerating new growth. Do not prune into this area.

Junipers (Juniperus)

This diverse group of plants includes spreading, upright, pyramidal, and creeping habits. All junipers can develop a dead zone in the center of the plant because of insufficient light. New growth will not develop from this area unless new buds are visible along the stem. Severe pruning is not recommended.

To prune for maintenance of size and shape, prune before new growth starts in the spring. Prune juniper branches at the point where they form V-shaped angles. To encourage the plant to be wider (for spreading and creeping junipers), remove the more vertical side of the angle and favor the more horizontal side. To keep width under control and encourage a more upright plant (for junipers with a tree form or taller shrub varieties), remove the more horizontal part of the angle, leaving the vertical part intact.

Yews (Taxus)

Yews can be trees or shrubs of various sizes. They are slow-growing, long-lived plants that produce two flushes of growth per year. New growth will develop on old wood, making yews very tolerant of heavy pruning or shearing.

To maintain size on well-maintained yews, prune in late winter or early spring before new growth begins, removing some of the new shoots. If needed, yews can be pruned a second time in mid-June. To avoid stimulating new growth late in the season (thus preventing winter injury), do not prune yews after July.

Yews that have not been pruned regularly and have grown larger than desired will need heavier and more extensive pruning to return them to good shape. It will be necessary to remove older, thicker stems (wood that is about 2 years old). Prune branches back to where they join with another branch. This will open the plant to more light which will stimulate more growth. Be careful not to cut back into the dead zone where there are no buds. This type of pruning should be done in spring before new growth begins.