Bamboo should come with a health warning, writes Dr Terry Mabbett

BAMBOO appears to tick all the boxes as a living screen and blocker of unwanted sights and sounds. Rapid plant growth and foliar hardiness combine to provide a natural, living fence or hedge in no time at all, and what could be simpler and seemingly less sinister than a grass plant?

Bamboos are a diverse group of evergreen perennial flowering plants in the subfamily Bambusoideae of the grass family Poaceae, albeit much bigger than mainstream grasses and most possessing hard woody shoots.

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However, that’s not how experts trained to get rid of invasive and damaging plants view bamboo. They describe its ultrarapid spread causing structural damage to properties on a similar scale to Japanese knotweed. Shoots of these fast-growing woody grasses have been found in people’s homes after breaking through from the garden, causing experts charged with controlling invasive plants to call for bamboo to be sold with a warning to inform of the risk presented.

Nic Seal, founder of Environet, a Woking-based company specialising in the control of invasive plant species, says the public should be made aware of the risk that bamboo poses to properties and the wider environment.

Roots and rhizomes of some varieties can spread up to 30 feet, causing considerable damage to houses and other buildings within the plant’s reach. A combination of its destructive capabilities and durability make bamboo a high-risk choice for domestic gardens, with subsequent removal both costly and difficult to achieve.

With a greater compressive strength than brick or concrete, and as hard to snap as steel, bamboo presents a mighty adversary.

Bamboo invariably grows taller than indicated on the label. This bamboo ‘fence’ designed as a screen or ‘blocker’ has already reached a height of 20 feet.

Bamboo can grow into dense thickets as tall as shrubs and small trees but is botanically a grass and therefore without the traditional vascular arrangement seen in most trees.

This has implications and repercussions for chemical control because the systemic herbicides used to kill trees and shrubs cannot move through bamboo stems to exert control.

Bamboo is resilient and capable of holding its own with other highly invasive species including bracken and bramble.

The only practical and realistic way to get rid of an infestation and invasion by bamboo is to employ the so-called ‘energy depletion method’. This entails cutting the bamboo canes to ground level before new leaves appear and repeating the process every year to deplete the energy reserves stored in the underground plant parts, taking two or three years at least. Alternatively, it can be professionally controlled mechanically, which means excavating entire plants.

Bamboo’s subterranean system is capable of an all-consuming strangulation of gardens and large areas in parks and other amenity sites. The marauding underground networks of roots and rhizomes can penetrate brick, masonry, patios and even cracks in concrete.

Bamboo is essentially unfussy about soil type and climate and as such is able to thrive in a range of soils and within a range of temperatures and environments. All types of bamboo present problems but the worst culprits and offenders are the ‘running’ types of bamboo which possess a network of roots and rhizomes, the latter responsible for lateral spread. A rhizome is an underground, horizontally growing stem.

They have the capacity to spread laterally for up to 10 metres underground, and if left unchecked and untreated will invade neighbouring gardens and pose a threat to the foundations of houses.

Anyone still not deterred from planting bamboo should opt for the ‘clumping’ types, but even these can present problems if left in situ for a number of years, with plants invariably growing much taller than advertised. Nic Seal says the number of bamboo-related enquiries from the public has more than doubled in the last 12 months.

“It’s time for garden centres and plant nurseries to take some responsibility for the escalating problem faced by householders and others up and down the country who have bought bamboo in good faith with no warning of the risks involved,” Nic Seal told MailOnline.

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“The plain fact is that most bamboos are invasive – and I expect they would be a good deal less popular if gardeners were given the facts at point of sale. We’re regularly dealing with entire gardens that are a mass of bamboo rhizomes, and where homeowners have desperately tried to keep on top of the problem by cutting back or mowing new shoots as they emerge. However, once it’s on the run, the only way to deal with it properly is to excavate the root ball and dig out every lateral rhizome, which often means chasing them across boundaries into neighbouring gardens.”

This clearly presents potential problems relating to access. Mr Seal says he has even seen bamboo growing up between the skirting board and wall of a house, having encroached beneath the patio from next door’s garden and exploiting a weakness in the foundations.

Truly tropical bamboos produce big and extremely hard stems used widely in building and construction.

Advice from Environet is don’t plant any sort of bamboo, while highlighting mitigating measures for those intent on taking the risk. This includes the choice of a clumping variety such as Bambusa or Chusquea and planting the roots in a strong pot rather than directly into the ground. The pot should also be lined with a strong root barrier that will stop the bamboo roots breaking through its container and running wild. Bamboo canes and foliage should undergo hard, aggressive pruning on an annual basis to keep plant growth in check.

Bamboo is currently an arb problem but so was Japanese knotweed originally. However, Japanese knotweed infestations are now common in the wider environment, including some ancient woodlands, especially in urban and suburban areas, mainly due to fly-tipping of garden waste.

AUTHOR’S NOTE

Bamboo is not classed as an invasive species in the Wildlife and Countryside Act 1981 and as such there are currently no restrictions on planting.

Under the provisions made within Schedule 9 of the Wildlife and Countryside Act 1981, it is an offence to cause Japanese knotweed to grow in the wild. Since 2013, the seller of a property is required to state whether Japanese knotweed (Fallopia japonica) is present on their property through a TA6 form – the property information form used for conveyancing.

Fast-growing Leylandii conifer hedges, which were all the rage in the 1970s and ’80s, can now be subject to an order for removal or height reduction under the AntiSocial Behaviour Act 2003. They have been overtaken in preference by bamboo with equally disastrous consequences but no legal recourse to control.

Although none of these provisions currently apply to bamboo, legal experts who deal with claims relating to invasive plants believe it is only a matter of time before bamboo joins Japanese knotweed and conifers in these respects.

Truly tropical bamboos in their Asian homeland and other areas of the tropics as invasive alien species plants grow at truly phenomenal rates to produce canes up to 15 cm or more in diameter and tens of metres in height. Though invasive in nature, they are highly valued as materials for building and construction and interior decoration.