From Nick Turrell, The Guardian, Friday 7 December 2012.
In 1888 something very rare happened on a country estate in Wales: a plant genus was born. Ever since, it has been nothing but trouble. It has caused civil unrest, violence and even murder in its march across the country. Until recently it was the bestselling plant in every garden centre in Britain. As with rats, wherever you are, you’re never far from a Leyland cypress.
Its full name is x Cuprocyparis leylandii, which translates as “tree most likely to annoy your neighbours”. It was discovered on the 4,000-acre Leighton Hall estate, near Powys, after a Monterey cypress and a Nootka cypress – which in nature grow nowhere near one another – cross-fertilised and produced six seedlings. The new tree has become so infamous that it’s known by only one name.
Leylandii’s success is especially impressive when you consider that it can’t reproduce, which means that every plant we see today comes from cuttings and has been planted by humans. How did such a mundane tree become so popular? Because it’s evergreen and vigorous. A leylandii will grow three feet every year, so in no time at all you’ll have factor 50-style privacy, something our insular society finds irresistible. The trouble is, it won’t stop: the tallest one is already 40 metres (130ft) and still growing.
Live with it…
So what do you do if you have them (there’s usually more than one) in your garden or, worse, a neighbouring garden? Management is crucial: this is not a plant you can turn your back on, especially when it comes to the soil. While deciduous trees will enrich the soil with organic matter in the form of fallen leaves, leylandii will treat it like a student treats a bank account – it’s all take, take, take. Before long your soil will have turned to dust. You’ll need to compensate by heaping on leaf mould, garden compost or rotted manure in autumn and spring.
Any nearby plants will also have to contend with leylandii’s dense canopy. Fortunately, there are some that can tolerate dry soil and aren’t afraid of the dark. The most fearless of all is Mrs Robb’s bonnet(Euphorbia amygdaloides var robbiae). This evergreen ground cover plant looks far too pretty to be such a trouper, but plant it around the outskirts of the leylandii and it will soon spread where the sun don’t shine. So will Siberian bugloss (Brunnera macrophylla ‘Jack Frost’). This is not evergreen, but its delicate blue flowers, similar to a forget-me-not’s, more than make up for that.
For something taller you could try bear’s breeches (Acanthus spinosus). This tough perennial will produce flower spikes a metre high and its leaves will cover at least a square metre. For a splash of leaf colour, there’s the purple-and-white-foliaged Heuchera ‘Regina’. In the spring this clump-forming perennial produces flowers that are both good for cutting and attractive to bees.
If you want something complementary, try Cotoneaster lacteus. This evergreen shrub is a strong grower and, at three to four metres high, is tall enough to hold its own. Growing it in front of leylandii will show off its bright red autumn berries, too. Evergreen Mahonia aquifolium andMahonia x media ‘Charity’ are smaller at 1.5 metres but will produce cheerful, fragrant yellow flowers in winter.
…or get rid of it
But what if the leylandii is in the garden next door? Any overhanging branches can legally be cut back to the boundary line. This goes for roots, too, and whoever owns the land the tree is growing on may be liable if it causes damage. In 2005, new legislation meant local councils could force owners of nuisance hedges more than 2m tall to reduce their height (visit rhs.org.uk for information about how to complain about a hedge). But it’s the parts you can’t see you should worry about. Leylandii roots extract so much water that they can cause clay soil to shrink, leading to subsidence in buildings.
Simply felling the culprit isn’t always the solution. If the tree has been taking out significant amounts of water, removing it may cause the soil to rehydrate and swell. This “heave” can be just as damaging. A large tree should be cut down in stages, which allows the soil to adjust. Some insurance companies ask if there are any trees taller than 10 metres growing within five metres of your property. If it’s a leylandii, your premium could be higher.
Cutting back overhanging branches shouldn’t be left too long, either. If you cut back too much in one go, it won’t regrow and you’ll be left with a brown patch. Simon Richmond, technical officer at the Arboricultural Association, says the key to pruning leylandii is little and often. He recommends pruning them twice a year once established, in late spring and again in late summer.
He also warns of the disease Kabatina shoot blight, which causes brown patches. “Sometimes the tree will recover if you feed and water it – but sometimes the only thing you can do is remove it, which isn’t ideal if it’s in the middle of a hedge.”
If you’d prefer a better-behaved evergreen screen, try holm oak (Quercus ilex), a broadleaf tree that responds better to close pruning. If it’s a conifer you’re after, try Thuja plicata or Chamaecyparis lawsoniana‘Pembury Blue’. My favorite conifer, however, is yew (Taxus baccata); this slow-growing tree is proof that good things come to those who wait.
High society: Leylandii trees in a large hedge. Photograph: Martin Godwin