How to prune conifer hedges for a stunningly effective privacy screen

With their evergreen appeal and rapid growth, it's little wonder that conifers are such a popular choice for hedges. That being said, though, they do need to be trimmed regularly if you want them to look their best – so how do you prune conifer hedges like a pro?

One of those plants you should prune in September, conifer hedges come in several varieties, including leylandii, Lawson cypress, and Monterey cypress.

Whichever graces your garden, though, they will need regular pruning to keep them looking smart (not to mention maintain your best plants’ health).

As ever, there's no point grabbing a pair of loppers and hacking away at your beloved bushes; there's a right way and a wrong way to prune conifer hedges, which is why it's best to consult the experts.

How to prune conifer hedges

"Pruning conifer hedges in the UK is essential for keeping them healthy, compact, and looking tidy," says Christopher O'Donoghue, one of the co-directors at Gardens Revived.

"Regular trimming will also help prevent the hedge from growing too large, which can become problematic with fast-growing conifers like Leylandii," he adds.

Christopher O'Donoghue

A gardener with almost two decades of experience under his belt, Christopher set up Gardens Revived with his brother, Andrew, in 2018 to create a thriving family business. Together, they have worked on residential gardens, listed buildings and gardens, flower shows and large estates with some exceeding 70 acres – many with historical significance.

What you will need

If you want to make sure yours are the best privacy plants, you need to learn how to prune conifer hedges like a pro – which means you'll want to arm yourself with the correct tools.

"Don't forget to wear gloves and eye protection, especially if using power tools," cautions Christopher.

To that end, then, you'll want to get hold of...

• Hedge trimmers
• Secateurs
• Loppers
• Ladder: Try an Aluminium Step Ladder from Amazon for reaching the top of taller hedges.

Step-by-step guide:

Once you have your tools to hand, it's time to learn how to prune conifer hedges so they look lush and trim.

Thankfully, much like learning how to deadhead plants, it couldn't be easier, thanks to our expert advice...

1. Choose the correct time

As is so often the case with gardening, it's not just a case of learning how to prune conifer hedges; it's important to know when to tackle the job, too.

“The best time to prune conifer hedges is from spring until late summer,” says Christopher, who says August/September is usually the cut-off point for this as pruning during colder months can expose the plant to frost damage.

"The new growth (called 'candles') will have started to harden, and pruning during this period will encourage denser growth."

2. Aim for a tapered shape

Whatever variety of conifer hedge you're working with, it's best to always trim it so that it is slightly wider at the base than the top.

"This helps ensure that sunlight can reach the lower branches, preventing them from becoming bare," explains Christopher.

3. Begin pruning in earnest

If you're not sure how to prune conifer hedges, it's best to begin by trimming the new growth on the sides and top of the hedge.

'Only remove about 1/3 of the new growth to maintain the hedge's shape,' says Christopher, who notes that it's vital you step back regularly to view your progress and ensure the hedge remains even and symmetrical.

"It's better to prune little and often rather than a heavy, infrequent cut. Regular, light pruning encourages healthy growth and keeps the hedge dense."

4. Remove dead and diseased branches

Just as is the case with pruning roses, you should cut any dead, damaged, or diseased branches back to the nearest healthy growth.

"Avoid cutting into old wood on many conifer species, as they don’t regrow from these areas," warns Christopher.

5. And on that note...

When learning how to prune conifer hedges, take care not to cut back into brown or old wood and stay in the green.

"Conifer hedges like Leylandii and most others will not regrow from old, brown wood," says Christopher, "so always prune only the green, younger growth, as cutting into old wood can leave permanent gaps in the hedge."

6. Get shaping

If you want to learn how to prune conifer hedges like a pro, you need to focus on shaping the top and sides.

"For a more formal look, trim the top of the hedge flat. Use a string line as a guide if you need help keeping it level," says Christopher. "For an informal look or in regions with heavy snowfall, a gently rounded top may be more suitable, as it allows snow to slide off."

He adds that you should work in sections on the sides, trimming them from the bottom up and keeping your cuts even and smooth.

7. Show it some love

While you should leave grass clippings on your lawn, the same is not true of conifer clippings around your hedge, as they can promote pest and disease build-up. Compost them, then, if you can.

Once that's done, Christopher advises you "give your hedge a good watering after pruning to help it recover and promote new growth".

"Apply a layer of mulch around the base to retain moisture and protect the roots," he adds.

FAQs

When should conifer hedges be trimmed?

If you're wondering when conifer hedges should be pruned, it's best to avoid late autumn and winter.

"If you do, the cuts won’t have time to heal before the cold weather hits," says Christopher O'Donoghue of Gardens Revived.

Instead, aim to prune your conifer hedges between the late spring and the end of the summer, with September as your absolute cut-off point.

"Before pruning, check for bird nests, as it is an offence under the Wildlife & Countryside Act 1981, to damage or destroy the nest of any wild bird while it is in use or being built," caution Royal Horticultural Society (RHS) experts.

How do you reduce the height of a conifer hedge?

If you want to reduce the height of a conifer hedge, you can do so by up to 1/3 in April, taking care to focus your attention on unsightly side branches.

"Fast-growing conifers like Leylandii should be trimmed at least once a year to prevent them from becoming too large. Twice a year may be necessary for faster growth," says Christopher O'Donoghue of Gardens Revived, who adds that you should never cut back too hard.

"Avoid cutting back into brown, old wood, as your hedges will not regenerate from this, leaving bare patches."

Now that you know how to prune conifer hedges like a pro, you can run and get your loppers. After all, you'll need to be quick if you want it done before winter hits...