What Time of Year Do You Trim Box Hedges?

For hundreds of years, boxwood hedges have graced formal gardens in Europe and the Americas. Overall, these hardy shrubs require little upkeep. But they need proper trimming – at the proper time – in order to look their best! Not everyone knows how to care for their boxwood or at what time of year do you trim box hedges. This article will cover all the basics of cultivating a beautiful box hedge – which will leave your garden looking spectacular.

What is a box hedge?

Boxwoods, or Buxus sempervirens is a hardy shrub native to most of the United Kingdom. They were first brought to the American colonies in the mid 1600’s.

There are over 150 cultivars found among the thirty-or-so species of buxus. They can range in size from small-leafed dwarf varietals that top out at 1’ tall all the way up to a 20’-high, larger-leafed cultivar.

Boxwood can thrive anywhere in your garden. It’s tolerant of almost all soil types – except very boggy or waterlogged ground – and is comfortable in both sunny and shady locations. Compared to cedar or other evergreens, is a slow-growing hedge species and is very low-maintenance. With proper care, boxwood can live for hundreds of years.

Are boxwood hedges out of fashion?

As beautiful as it is, boxwood has fallen out of favour with some modern gardeners. Throughout history, they’ve been trimmed into severe geometric shapes and intricate patterns – or even topiaries, fanciful living garden statues – all of which don’t fit in well with the more casual modern garden plans that have become trendy over the past decade of so.

And what’s more: the hours of trimming and shaping that it took to keep them perfectly in line don’t fit with our busy modern lifestyles. But boxwood doesn’t truly need all that trimming to look beautiful.

In fact, many of the varietals naturally grow in lovely shapes and can thrive with little or no intervention.

Does a box hedge need to be trimmed every year?

bright green box hedge leaves

If you plant to include formal box hedges in your garden, you will need to trim your shrubs regularly. To maintain the desired shape of your box hedge, it’s best to prune it twice every year.

After the first growth spurt and once the risk of frost has passed – typically in the late spring – you should trim the new growth of your box hedges. Time the second pruning for late August or early September – trimming can encourage a burst of growth, and you don’t want to risk any new growth being killed off by winter weather.

Regularly thinning your boxwood will also make shearing easier, as it will leave fewer of the stiffer, heavier branches to cut through when pruning and shaping your hedge.

Why should you trim a box hedge?

Boxwood, like any other shrub, needs regular pruning to keep it at its best – primarily shape it, but also to clean out the dead or twisted branches that can be harmful to your bushes. And if you neglect regular pruning, you’ll soon find a shaggy wall of evergreen foliage looming over your garden.

Properly shaping the plant will eliminate a “shouldering” effect, where the hedges bulge out at the top and centres and shade out the bottom of the plants.

Your box hedge can also become very dense at the top and sides if you shear it during and active growth period – as this will encourage branching. This creates a type of thicket at the outer edge which blocks light from the interior and stunts the growth of the inner branches, leaving your hedge a hollow ball. You’ll want to thin out your hedge to promote healthy, even growth throughout the plant.

How should you trim your box hedge?

As a general rule, choosing a shrub that matures at the height you need for your space will reduce the need for drastic pruning. If you’re growing them as a full hedge, avoid pruning on the side between the plants as you want them to grow together over time.

For larger hedges, you can use an electric- or gas-powered trimmer to save time, but hand shears and pruners will make cleaner cuts and keep a straighter shape more easily. You only ever want to use sharp blades for trimming your box hedges. You can also use a household antiseptic cleaner or a solution of 1:10 bleach to clean your tools and prevent the spread of disease or fungus from other plants onto your boxwood.

If you trim in wet weather, or wet the leaves before pruning, the cut ends will heal quicker which helps to prevent disease. You may also want to keep a bucket of water at hand while pruning. Boxwood sap can stick to the blades – and it’s important to rinse them off periodically so that they remain sharp while you trim.

Trimming boxwood for formal gardens

For more formal gardens, you’ll want to maintain more geometric and straight-sided box hedges. In fact, many gardeners choose to mark their cut lines with string guidelines before beginning.

You should start by trimming the sides of the hedge and leave the top until the end. Ideally, your box hedge should be slightly wider at its base and taper gradually toward the top. In order to achieve perfectly straight lines, try keeping your shears or clippers at the same height when trimming.

If you’re dealing with an overgrown box hedge that hasn’t been tended in quite some time, you have a couple of options. While severe pruning can have mixed results, larger hedges can often handle losing up to 2’-3’ depending on their size, health, and the time of year.

Your first option is to rejuvenate the root system by cutting the boxwood to within a foot or so of ground level – you can then train the new shoots over the next few years. You may also choose to remove about one third of the oldest, largest branches every year over a 3 to 5-year period until all the old overgrowth has been removed.

So, when is the best time of year to trim your box hedges?

In order to maintain the shapes of your hedge, you should trim back the first burst of growth after the risk of frost – in late May or early June. Cut them to a couple of leaves above the start line of the current growth, which is a lighter green than last year’s leaves.

You can trim the hedge once more before the end of the growing season – no later than October – in order to keep them tighter over the winter. If you trim too late in the season, your hedge may not heal before the winter. If that’s the case – or if you’re drastically pruning an overgrown shrub, you should wait until late in the dormant phase to trim your boxwood.

If you prefer to only trim your hedges once a year, then cut your boxwood back in mid-to-late July, but they many grow back as densely.

The choice is yours. How much time would you like to spend in your garden this season?