When to trim your box hedge — when, why & how!

Are you considering a bit of topiary? Do you gaze upon your neighbour’s excellently pruned or shaped box hedges with envy, wishing you had the skill and confidence to shape your hedge without damaging the plant? And when to trim box hedge – that eternal dilemma!

Box hedges are stunning evergreens that you can carve into interesting shapes. But if you prune incorrectly, you can damage the plant! So, to ensure that the plant continues to grow densely and vigorously, you need some expert tips. 

And that’s what you’ll get if you read this article — all about how and when to trim box hedges. We’ll explore how to cut using the right tools, including a step-by-step guide to box hedge cutting. 

So, let’s get started, shall we?

What is a box plant?

A box plant is an evergreen bush that belongs to the Buxaceae family. It’s popular in gardens across the planet due to its dense branch networks, small, leathery leaves, and ability to hold shape for a decent time period. 

Box hedges are probably one of the more satisfying hedges to trim and carve, giving your garden a noble touch with bushes cut into a range of shapes, including:

• Spheres
• Pyramids
• Boxes
• Animals 
• Machines

In fact, it’s possible to transform a box hedge into literally any shape — your imagination is literally the limit! 

The needs of the box plant

Box plants are hardy and versatile — happy in sandy, well-drained clay soil and full sun or partial shade. 

The plant’s slow growth makes it a boon for those of us who would rather not spend every couple of months pruning and a bonus for the more creative among us who enjoy nothing more than shaping our box hedges into interesting shapes. 

Types of box hedge

There are several Buxaceae varieties, including:

• Common box plant (Buxus sempervirens)
• Small-leaved box plant (Buxus microphylla)
• Japanese box plant (Buxus japonica)

Cutting a box plant — more than just art?

Regular pruning keeps your box plant healthy and in good shape. But there are several reasons why pruning your buxus is an essential garden task:

• Maintains the desired shape and design
• Removes old, dead, and potentially diseased wood from the plant
• Better air circulation minimises the potential for pests and diseases
• Prevents the plant from growing too big

Topiary vs Trimming — when to cut box plants

There’s a clear distinction between an annual trim and a shaping:

Topiary

Topiary is the art of shaping plants into interesting and fantastical shapes. This means you’ll cut some areas deeply while trimming others minutely. For best results, you should prune twice a year. 

Spring pruning

Complete the spring pruning before growth starts for the year once the threat of frost has passed. This pruning helps rid the plant of dead and damaged wood and foliage, which is excellent preparation for shaping.

This is an excellent time to check your plant’s condition after the winter. You may need to fertilise the plant after pruning, especially if the leaves are looking a little weak and pale. 

Late summer/autumn pruning

Your box plant’s principal growth period is over by the end of August/September, so this is a good time for reshaping, which helps regulate over-winter growth. The second pruning prepares the plant for the change in the weather, setting it up to bear the wet and frosty winter months. 

Of course, you can never quite rely on the UK’s weather, and there’s as likely to be a mini-heatwave in October as rain in July! So, avoid hot weather or direct sunlight for pruning, which can burn and stress the plant. 

A cool, cloudy day is ideal. Or what for the late afternoon if there are unseasonally high temperatures?  

Trimming

While box plants grow relatively slowly, you may need to trim every four weeks to maintain complex shapes. 

However, make sure these interim trims are trims — not scalpings! Over-pruning will weaken the plant, making it susceptible to pests and disease.

Do you have other hedges or plants in your garden ready for a trim? Check out our expert pruning articles. 

The correct pruning tools for box plants!

You’ll get the best results when using the right tools. 

So, I recommend using the following:

• Secateurs — ideal for trimming thinner branches, long shoots, and making precise cuts for topiary.
• Hedge trimmer — perfect for more extreme shaping
• Hand saw — offering the safest way to remove thick or hard branches 
• Gloves — to protect your hands against sharp branches, which can easily cut your hands

But, perhaps, the most important tool of them all for the expert topiarist is the sharpening tool. Never use blunt tools to cut into your plants — the blunt edge tears the plant rather than slices, leaving a larger wound, which is much more prone to infection. 

Use a tool, such as a grindstone, to sharpen the blades of your cutting tools, and remember to clean the blades thoroughly before and after each pruning. 

A step-by-step guide to guide to topiary cutting

These steps will help ensure an outstanding result that won’t stress the plant:

1. Sharpen, clean, and dry your tools, especially the cutting tools. 
2. Spread a tarp underneath the plants, around the base, to catch the cuttings. It makes it easier to tidy up afterwards. 
3. Thin out the dead, diseased, thin, and weak branches down to the next healthy shoot or stem. 
4. Remove unwanted thick branches.
5. Use string or a folding rule as a stencil for your desired shape. And cut gradually, avoiding big cuts when shaping the plant. Remember, you can always cut shorter — you can’t elongate a short branch! 
6. Go slow, and keep standing back to assess your work as you go. Don’t be tempted to over-cut — be conservative with each cut — standing back to take in the bigger picture. 
7. Remove the tarp and collect any excess waste. 
8. Fertilise and water the plant. Give it plenty of water (but avoid waterlogging the soil). Box plants like well-drained soil. 

Box plant pruning aftercare

Keeping your plant healthy is the best way to help maintain its growth and shape. So, follow these aftercare tips for excellently healthy box plants:

• Water regularly, especially after trimming and cutting. 
• Ensure the soil drains well. If you have clay soil, you may need to dig in a soil improver to help prevent root rot and water-logging. 
• Fertilise with a good quality product at least once a year — twice ideally. Use a slow-release formula to prevent shocking the roots. 
• Add 5-10cm of mulch around the plant’s base. This reduces weeds and protects the roots from extreme temperatures. 
• Check for pests and diseases regularly. Common culprits are box plant border, fungal infections, and powdery mildew. 

Dispose of box plant cuttings wisely!

Box plant cuttings are poisonous, so use local council green bins to dispose of the cuttings. Chop the waste into small sections, and mix it with other organic waste, such as leaves, garden, and kitchen waste. 

However, you can also compost box cuttings — but don’t use the compost on fruit and vegetable beds.

Common mistakes to avoid when trimming box hedges

Box plants are relatively straightforward plants to maintain. However, there are some common mistakes to avoid, which can affect the plant’s vitality. These include:

Excessive pruning — this causes stress and stunts your plant’s growth. Make regular, light cuts every four weeks to maintain your desired shape. 

Pruning in hot temperatures — this causes burns on cut sites and puts the plant under stress. Choose a slightly cloud, cool day instead. 

Use dirty or blunt tools — if you want to infect your plant with diseases, use dirty tools. Always use clean, sharp cutting tools to maintain the plant’s health, ensuring a precise, small cut. 

Pruning at the wrong time — avoid pruning during the winter, when the plant is dormant. 

FAQs

Ready to get started?

I hope I’ve provided all the information you’ll need for successful box plant pruning. But if you have questions, don’t hesitate to email us.

Alternatively, check out our comprehensive Help & Advice section, offering expert tips on everything lawn and garden orientated. 

Thanks for reading!