European hornbeam (Carpinus betulus) as a hedge in New Zealand

Quick answer: European hornbeam grows about 30 to 50cm a year and reaches 2.5 to 3.5m tall by 1.5 to 2m wide after five years as a clipped hedge. It takes heavy, cold, damp ground that beech will not, and it holds dry brown leaves right through winter if you give it its main trim in late summer. Space at half the height you want to hold it, so 90cm centres for a 1.8m hedge.

Drive past a hornbeam hedge in the middle of July and every leaf on it is the colour of a paper bag. Dead, all of them. Not one on the ground. They rattle when the wind gets into them, and you still cannot see the house behind.

People plant it for exactly that: a formal hedge that still screens in July, on ground where beech would have died in its second winter.

So here is the full picture on European hornbeam: how fast it moves, what it will grow in, how far apart to plant it, and where I would leave it alone.

What does hornbeam do that beech will not?

It grows on heavy, wet-in-winter ground.

Beech and hornbeam get sold as the same idea, and they do look similar in a clipped hedge. The difference shows up under the ground. Beech has a shallow root system that rots in soil which stays saturated through winter, and on tight clay it either dies back or sits there sulking for years. Hornbeam handles the same ground and keeps going. UK hedging references, which have far more mileage with both species than we do, are consistent on that point.

Second difference: wind. New Zealand nurseries rate beech as temperamental in wind and on exposed coastal sites, and hornbeam as the tougher of the two.

What you give up is the autumn colour. Beech turns copper and holds a warm russet all winter. Hornbeam turns yellow, then browns off to that paper-bag colour. Some clients love it, some think it looks dead. Show them a photo in July before you order 60 plants.

Does it hold its leaves all winter, or is that a sales line?

It holds them, with a condition attached. The condition is that you trim it.

The habit is called marcescence: dead leaves stay attached instead of dropping. It shows up strongest on young, juvenile growth, and clipping a hedge keeps it producing young growth indefinitely. A hornbeam left to grow into a 12m tree drops most of its leaf and only keeps a few on the lower branches. A hornbeam trimmed as a hedge in full sun holds the lot.

Timing matters too. Give it its main annual trim in late summer, once the season's growth has slowed, and the fresh shoots it makes after that cut are the ones that hold leaf through winter. In our seasons that is February into early March.

Down here the old leaf usually hangs on until the new buds push it off in spring, which is September or October in Southland and Central Otago.

If you’re a landscaper selling it to a client, be straight with them about what winter looks like. Standing right against the hedge you will see slivers of daylight through the brown leaf. From ten metres back you will not.

How fast does it grow, and how big does it get?

About 30 to 50cm a year, and 2.5 to 3.5m tall by 1.5 to 2m wide after five years as a hedge.

Left to be a tree it goes a lot further. Southern Woods list it at 4m after five years and 12m by 7m at maturity, with a medium growth rate. So the hedge figure and the tree figure are the same plant under two different management regimes, and the only thing keeping it at 2m is you, twice a year, for as long as you own the place.

Pick the height before you plant. A hornbeam hedge held at 1.5m is a pleasure. One that got away to 4m before anyone made a decision is a hire-a-scissor-lift job.

How far apart should you plant it?

Half the height you intend to hold the hedge at.

• Held at 1m tall: 50cm centres.

• Held at 1.5m: 75cm centres.

• Held at 1.8 to 2m: 90cm to 1m centres.

That is our rule across every hedge species and it is deliberately wider than what you will see published. The Plant Store, for instance, recommends 60cm centres for a dense hornbeam hedge. Their figure is not wrong so much as it is aimed at closing the row faster, and it sells you more plants per metre. At 90cm centres a 20m hedge takes 23 plants. At 60cm it takes 34. You will wait perhaps a season longer for the row to knit at the wider spacing, and then have a hedge whose plants are not competing with each other for the next thirty years.

When do you trim it, and how do you get the base to fill?

Main trim in late summer. Formative tip pruning on young plants in late winter.

The Plant Store's advice on establishing a hornbeam hedge is to nip 1 to 2cm off the tip of every shoot in late winter while the plant is still dormant and the buds are only starting to swell. Taking out the terminal bud stops the shoot running upward and wakes the side buds below it. Repeat lightly through spring and early summer as new growth appears.

That sounds fussy for a big row, and on a 200m boundary it is. But the alternative is the classic mistake: leave it alone until it is tall, then try to make the bottom fill in. By then it will not. Hedges thicken from the base upward in the first two or three years and after that you are maintaining whatever shape you trained.

Will it take a Central Otago frost?

Yes, comfortably. Cold is not the thing that kills hornbeam here.

Carpinus betulus is rated hardy to USDA zone 4, which is a winter minimum well below anything New Zealand produces. Alexandra, Ranfurly, Lumsden, none of that is testing it. NZ nursery listings describe it as suited to frost pockets and to the cooler regions generally: the South Island, inland Canterbury, Wellington and the lower North Island.

Which makes it one of the few formal hedge options where I do not have to give the usual speech about protecting young plants through their first winter.

Where would you not plant it?

Three places.

Ground that is under water rather than just wet. Hornbeam takes heavy and damp. It does not take permanently waterlogged. If the spot has standing water in it for weeks at a time, it is a job for a sedge or a rush, not a formal hedge of any species.

Where the client wants a screen that looks green in August. It will not. If somebody is buying privacy from a neighbour's upstairs window and they are going to be looking at it every winter morning through the kitchen glass, have the conversation before they sign off the plan, not in year two.

Tight against a boundary or a services line. A plant that will make 7m of spread if you stop trimming has a root system to match.

What would you plant instead if it has to be evergreen?

Two natives that hold their leaf and take a cold, damp South Island site.

Coprosma rubra is a red-stemmed evergreen that grows naturally on river terraces and in damp sheltered shrubland, and gets to 2 to 3m over a good many years. It is slow. Sources also split on how much wet it truly wants, with NZPCN describing it in riparian forest and damp shrubland while nursery listings call for free-draining soil, so on a soggy line I would trial a few before committing a row.

Podocarpus nivalis, snow totara, is an alpine plant by origin and takes frost, wind and exposure that would flatten most hedge species. It clips to a low, dense hedge with one or two light trims a year and sits between 50cm and 2m depending how you manage it. Slower than hornbeam by a long way, and a different look entirely, but it will still be there in fifty years.

Neither one gives you the formal, flat-faced, architectural look of a clipped hornbeam. If that specific look is the brief, hornbeam or beech is what the brief needs.

Common questions

Is hornbeam the same thing as beech?

No. Beech is Fagus sylvatica, hornbeam is Carpinus betulus, and they are not even in the same family. They get confused because both hold dead leaves through winter in a clipped hedge and the foliage looks similar at a glance. Hornbeam leaves are more deeply ribbed and a bit tougher in the hand.

Can you buy hornbeam already grown as an instant hedge?

Yes, several New Zealand growers sell it in large grades and as pleached stems on a clear trunk, which is the trick for screening an upstairs window without losing the ground-level view. Expect to pay accordingly.

Does hornbeam work as a low hedge, under a metre?

It does, though it is a lot of trimming to keep a naturally 12m tree at knee height, and the leaf is large in proportion at that scale. For anything under about 800mm there are better-suited species. Above 1.2m it starts to make sense.

When can it go in the ground?

Any month, if the plant is containerised. Bare-root and field-grown hornbeam is a winter-only proposition because the plant has to be lifted while dormant. Container stock carries its own roots and mix, so autumn is best, winter is fine, and even a late planting works if somebody commits to watering it through the first summer.

Hornbeam is the answer to a fairly narrow question: a formal, deciduous hedge that screens in winter and grows on ground that would see off beech. Where that is the brief, nothing else does it better. Where it is not, there are easier plants.

Contact us