How far can you cut back a conifer hedge?

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Can I Prune Conifers – Pruning Coniferous Trees

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Table of Contents Show

Can I Prune Conifers – Pruning Coniferous Trees
When and How Can I Prune Conifers?
First, ask why?
Then ask what and how?
Fanlike needles
Flat needles
Bunched needles
Stiff needles
Can you cut a conifer hedge right back?
Can you cut the top off a conifer hedge?
Can I reduce the height of a conifer?
How do you trim a tall conifer hedge?

While pruning deciduous trees is almost an annual ritual, pruning coniferous trees is rarely required. That’s because the tree branches usually grow in well-spaced and lateral branches have little effect on the growth of the central leader. Sometimes, though, cutting back conifer trees is necessary.

The question is not “can I prune conifers?” but “should I prune confers?”. For more information about when and how to prune conifers, read on.

Pruning a conifer is quite different from pruning a broadleaf tree. A broadleaf tree requires pruning to create a stable structure for the tree, correct the spacing of lateral branches, and to make sure no branches push out the center leader. Pruning can also be done to balance the shape of the tree or reduce its size.

Conifers generally don’t need this type of pruning since they grow in a pyramid shape, making random shaping unnecessary. The lateral branches of conifers are naturally spaced appropriately. Finally, given the growth pattern of a conifer, it is hard to prune a conifer to reduce its size unless you are sheering a hedge.

This doesn’t mean that you should never take pruners to a conifer. Pruning of conifers can be very important, especially when you are cutting back conifer trees to remove dead wood or damaged branches. It is just as important to take out dead and dying branches in conifers as in broadleaf trees. This type of pruning is partially for aesthetics, but safety also plays a role. Pruning out failing limbs prevents them from collapsing and endangering people nearby or the tree itself.

When and How Can I Prune Conifers?

We often have readers ask us, “can I prune conifers?”. Of course, you can! The trick is to make sure that you only do pruning of conifers when it is absolutely necessary. That’s because conifers do not have latent buds like broadleaf trees do that will grow into a full branch after pruning. Absent visible buds on a conifer, old wood that you prune, will likely remain a bare stub rather than a place from which new growth will sprout.

When is pruning coniferous trees appropriate? Many people like to prune out lower branches to allow for passage below the tree as the tree becomes mature. Done correctly, this pruning will not weaken the tree.

First, cut the underside of the branch about 1/3 of the way through several inches above the point where the final cut will be made.
Next, saw through the top of that undercut to remove the branch at that point.
Last, make the final cut near the trunk preserving the branch collar.

It is also a good idea to prune a conifer if it has twin leaders. Select one of the two and remove it to allow the other to take over. Use clean, sharp, sterilized equipment and err on the side of conservative pruning. You can always remove more later.

This article was last updated on 11/04/22

First, ask why?

Prune for size control.

Back in college, my professor used to rant, “Never prune conifers without a darn good reason.” (Actually, his language was a little saltier than that.) The point is to remember that there is no place for recreational pruning of conifers because they don’t replace growth like other trees and shrubs; pruning is always done for a particular purpose.

Form

The pyramidal form many of us want from our conifers results from their strong apical dominance. This means a single leader branch dominates and suppresses the growth of other shoots. Occasionally, two or more terminal leaders may become dominant, creating a Mohawk look, or the main leader grows quickly, making the tree look like it has a rocket shooting out the top (see photo above). These conditions can make your lovely tree resemble a nondescript shrub. Extra leaders can also develop into branches that have poor attachment angles and are often the first to break in storms.

Size control

In some ways, this is the weakest reason for pruning. If we plant the right tree in the right place, tree size should not be an issue. Almost all gardeners, however, have found themselves in the position where a tree grows faster than anticipated into other plants or buildings, and the need to keep that conifer in check arises.

Prune for health.

Health

Removing dead, diseased, or damaged branches should be done anytime a problem pops up and can be safely corrected. Removing branches that cross and could potentially rub against each other is important because these injuries can be an entry point for disease. Limbs that appear weak because of poor attachment angles (called a narrow crotch) should also be pruned away. As the tree grows, excess bark accumulates in the crotch. This results in weakness because, over time, more bark and less wood holds the branch to the trunk.

Video: Pruning Conifers for Health

Rehabilitation

With few exceptions, conifers will not resprout if cut all the way back to the base, unlike many deciduous trees and shrubs. It is possible, nevertheless, to rehabilitate old, unsightly conifers with some drastic and creative pruning that can result in a new, pleasing look.

Before

After

Then ask what and how?

Conifers include a wide array of plant types, all with different types of needles, which all respond differently to pruning. This is due to differences in growth patterns: when the tree sets new buds, pushes new growth, or stops growing altogether. When you prune is largely dependent on these growth patterns. Here are some identification tips, timing guidelines, and pruning methods for the most common conifers.

Fanlike needles

Arborvitae

Juniper

Chamaecyparis

Arborvitae (Thuja spp. and cvs.)

Needle structure: Soft, fanlike needles form sprays along the stems. The foliage feels scalelike to the touch. There are no markings on the undersides.

When to prune: When pushing new growth in late spring or early summer.

Junipers (Juniperus spp. and cvs.)

Needle structure: The foliage is borne on branches in sprays. It’s sometimes easiest to eliminate every other category before deciding it’s a juniper.

When to prune: When pushing new growth in late spring or early summer.

Chamaecyparis (Chamaecyparis spp. and cvs.)

Needle structure: The sprays of foliage are similar to junipers, but many have silvery X markings on the undersides.

When to prune: When pushing new growth in late spring or early summer.

Snip branch tips back lightly.

Pruning method for arborvitae, juniper, and chamaecyparis

Unlike some conifers, these trees will not form new buds on old wood. So if you cut back to the brown, aged stems, it won’t grow back. Pruning for size control, therefore, can only be done on new growth (where the stems are still green and pliable). Snip branch tips back lightly.

Video: Pruning Arborvitae, Juniper, and Chamaecyparis

Flat needles

Hemlock

Yew

Hemlocks (Tsuga spp. and cvs.)

Needle structure: Short, flat, dark green needles are slightly stiff. The undersides of the needles have two white bands.

When to prune: When dormant in late winter or late summer.

Yews (Taxus spp. and cvs.)

Needle structure: Short, soft needles are flat with a tapered tip and occur only on one side of the stem.

When to prune: When dormant in late winter or late summer.

Lightly trim back the outermost growth using hand pruners or hedge shears.

Pruning method for hemlock and yew

To help shape these trees into formal hedges or to encourage fullness, lightly trim back the outermost growth using hand pruners or hedge shears. These conifers get a flush of new growth after pruning, so the best time to give them a haircut is when they are not actively growing.

Bunched needles

Pine

Pines (Pinus spp. and cvs.)

Needle structure: The branches bear needles (oftentimes long) in groups of two, three, or five.

When to prune: When pushing new growth in late spring.

Cut with hand pruners.

Pinch to desired length.

Pruning method for pine

Pines should be pruned during active shoot growth because this will allow sufficient time for the shoot to produce a new set of buds for next year’s growth. The current year’s new shoots, or “candles,” can be cut with hand pruners or simply pinched off to the desired length.

Video: How to Prune Pines

Stiff needles

Douglas firs (Pseudotsuga menziesii and cvs.)

Needle structure: Needles are arranged in a spiral around the stem. If you crush them in your hands, they will smell like Froot Loops.

When to prune: When dormant in late winter or late summer.

Firs (Abies spp. and cvs.)

Needle structure: Stiff needles appear singly, up and down the branch. If you pull off a needle and roll it between your fingers, it will feel flat and won’t roll easily.

When to prune: When dormant in late winter or late summer.

Spruces (Picea spp. and cvs.)

Needle structure: Needles are extremely sharp (it’s the deadliest Christmas tree you can pick) and are borne singly all around the stem. These four-sided needles roll easily between your fingers.

When to prune: When dormant in late winter or late summer.

Make a cut half an inch or so above a bud.

Trimming back the outermost tips encourages fullness.

Pruning method for fir, Douglas fir, and spruce

To control height, prune the leader while the trees are dormant. These conifers form buds along their stems, so make a cut half an inch or so above a bud. The topmost bud will become the new leader. This cut will also stimulate outward growth of the buds below.

Lightly trimming back the outermost branch tips during dormancy will also encourage fullness when the tree pushes new growth in spring.

Video: How to Prune Fir, Douglas Fir, and Spruce

Can you cut a conifer hedge right back?

A conifer should only ever be trimmed within the boundaries of its green needles, cut too far and you hit brown and there's no going back.

Can you cut the top off a conifer hedge?

Evergreens should not be topped, or cut off at a certain height, because this will produce trees that are anything but attractive. Trees that are topped are also at a greater risk for disease and other ailments. Do not prune conifer trees too late in the year.