• Lewis Dean Estate & Letting Agents

The bamboo invasion – why you should be more worried about it than Japanese knotweed

Article by Val Borne - The Daily Telegraph

There’s been an alarming report about a bamboo invasion in Hampshire, with the plant breaking through the walls of a neighbouring property, reaching under the floorboards and heading up through the cavity towards the bedrooms above. I’m not at all surprised, because in the late 1970s – when I was a strapping young mother with immense stamina honed by two children under two – I agreed to help a friend clear a stand of bamboo on heavy clay soil in Northamptonshire. It broke my spade, it broke my back and it broke my spirit as well.

The roots were an impenetrable jungle, because bamboo is possibly more invasive than Japanese knotweed, another concrete-breaking alien you need to be wary of. That particular feathery-topped giant, eaten as a vegetable in Japan, has long held the title of the worst invasive plant in the world. It is thought to cost the UK economy around £165 million a year, thanks largely to its impact on property values.

Knotweed can certainly cause damage, but its risks to properties have been exaggerated. Last week, the Royal Institution for Chartered Surveyors announced it was updating its guidance on the plant, stating it should only affect the value of a home if it is causing visible damage to it. Meanwhile, a biological solution has arrived in the form of imported aphids, Aphalara itadori, which are being released in certain parts of the UK to suck the lifeblood out of knotweed stems. (They’re not currently allowed in Scotland, although the aphids may not know where the border is.)

So while knotweed’s reputation is showing some green shoots of recovery, attention is now turning to other invasive plants – such as bamboo. Like knotweed, some varieties can spread quickly via underground rhizomes, with the potential to damage buildings and cross garden boundaries.

But when it comes to fashioning a rustling windbreak, nothing creates a better magic lantern pattern on the ground more effectively than a trembling bamboo. They’re not so much windbreaks, they’re dreamcatchers. In the drier, colder gardens of East Anglia, at least. There, bamboo is likely to refrain from dangerous growth spurts and remain a statement plant.

However, when planted in the warm “banana belt” of southern or western parts of the UK, and encouraged by warm, rain-laden winds straight from the Atlantic, bamboo will behave much more aggressively. Here, it is likely to become a triffid.

Triffids are fine when there’s space to stretch, wander and roam – but they’ll break out of small spaces as effectively as the Incredible Hulk splitting the seams of his shirt. They’re not for small gardens, especially with the milder winters we’re getting now.

Garden centres sense our reluctance and try to convince us to grow the showiest ones in rugged containers. But still they dry out and sulk and refuse to develop handsome lacquered canes in shades of soot-black, gold or avocado green.

The secret, as with everything in life, is making the right choices. Ignore the rampant Chinese bamboo, introduced in the late-19th century from the lowland plains of China – unless you have a large estate or want to prevent soil erosion. Instead, head upwards into the mountains and go for more restrained clump-formers. They still need space and their growth habit is still affected by the soil and rainfall, but they don’t develop foot-shaped rhizomes that march away. Where space allows, these could be planted in the ground with root barriers, but not too close to boundaries or buildings.

Seek out Fargesia rufa, commonly called the Dragonhead bamboo, the preferred food of the giant panda. It fountains out from a tight base, reaching a height of 2.5m (8ft) x 1.2m (4ft) wide in 10 years. The sheaths round the canes are shrimp-pink, particularly so on alkaline soil. I’d be a little bit more wary about Fargesia robusta – the clue is in the name there.

Perhaps the most feathery group of bamboo are the chusqueas from Chile, but they need good drainage and a cool climate to thrive because they come from the high Andes.

Chusquea culeou, the Chilean bamboo, has refined foliage and olive-green canes banded in black. This award-winning, clump-forming bamboo makes an evergreen screen that will reach 4m (13ft) in height and achieve a width of 2m (5ft) after 10 years. It hates to be moved, but in time it can reach 8m (26ft). That could annoy the neighbours as well, but at least you can reassure them that it won’t spread or invade their home.

The most alluring bamboo, the one I have toyed with actually planting before (thankfully) recalling the Herculean labour of actually removing one, belong to a genus named Phyllostachys from China. They require a root barrier, when planted in the ground, but there are black-stemmed, golden stemmed and green-stemmed ones to tempt you.

When it comes to bamboo, go to a specialist and take their advice. If you don’t believe them, wander down to Trebah Garden in Cornwall and look up through the tree-like canes – and then go and buy a succulent instead.

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