Invasive bamboos and their comparable impacts

Daniel Docking from the Property Care Association investigates the threat of invasive bamboos.

Great Britain built its empire on the import and export of exotic goods, including materials, animals, foods, and plants. While importing exotic plants has long been a norm for the wealthy, it was during the early 19th-century Victorian era that garden nurseries innovated to meet the needs of an emerging middle class.

Unfortunately, some of these exotic plants have failed to integrate into our finely balanced environmental equilibrium, resulting in invasive non-native plants (INNPs). More recently, due to glamorous makeover shows and the ease of access to exotic plants delivered directly to our doors, we have exacerbated the problem first established by our predecessors.

Currently, over 50 per cent of flora within Great Britain is non-native, with an ever-growing list of these becoming invasive. Traditionally, Japanese Knotweed (R. japonica) has been seen as the poster child for INNPs, closely followed by Giant Hogweed (H. mantegazzianum) and Himalayan Balsam (I. glandulifera). However, an emerging threat similar to Japanese Knotweed has been identified: invasive bamboo species. These are typically found in residential gardens, spreading to neighbouring areas, growing through landscape features, reducing amenity value, and entering homes, yet their broader environmental impacts have yet to be calculated.

The problem

One of the main concerns with invasive bamboo species is identifying which species are, or could become invasive. Running species (Leptomorphs) are typically considered more invasive, by spreading through long, horizontal rhizomes that can extend several feet from the original planting site, making containment challenging. While clumping (Pachymorphs) are seen as “safer” options, although initially more contained, can also become problematic if not properly managed.

Over time, their dense growth can exert pressure on structures, paving, and other plants, causing similar damage to that of running species. However, like most invasive plants, they can adapt and overcome to ensure their survival. This means clumping species can sometimes spread beyond their typical means, adopting running tendencies to suit their environment. This adaptability is a significant issue because it complicates DIY control efforts.

Misidentification of bamboo species at nurseries further exacerbates the problem, as gardeners may unknowingly purchase running bamboo species which are labelled as clumping. This is compounded by the lack of adequate information provided at the point of sale on how to manage and contain bamboo, leading to widespread planting without understanding the potential risks. Consequently, even non-invasive bamboo species can become problematic if they are allowed to spread uncontrollably. Finally, and possibly the most influential part of the problem, is the skewed media narrative that portrays invasive bamboo as completely unmanageable, echoing the hysteria surrounding Japanese Knotweed in the early 2000s. This sensationalist comparison, dubbing invasive bamboo as “Japanese Knotweed 2.0,” unjustifiably elevates its threat level.

During the early 2000s, there were very limited options and expertise in dealing with a plant which was being headlined as being able to tear down a house. Those and similar narratives can cause unnecessary panic among homeowners and gardeners, leading to hasty and sometimes harmful management practices. Instead of fostering informed decision-making, this portrayal undermines balanced perspectives and overshadows the sheer number of experts readily available to implement measures available for controlling bamboo infestations.

A familiar threat

Few INNPs can rival Japanese Knotweed in terms of potential amenity value destruction and spreading capabilities. Invasive Bamboos, with their similar underground root growth patterns, could be considered a natural competitor, hence the media comparisons. Additionally, invasive bamboos can penetrate weaknesses within structural buildings and exacerbate pre-existing damage.

However, it’s essential to recognise that not all bamboos are invasive. Labelling all 1,500 different species globally as invasive would be disadvantageous. Many bamboo species can be valuable additions to a garden, offering aesthetic appeal without excessive invasiveness. However, what flourishes in one garden may not be suitable for another. Homeowners should conduct thorough research before selecting and planting any bamboo species.

The focus

The immediate focus should be on “invasive bamboos” as these pose significant threats to homes and nearby soft/hard landscape features. While this term could encompass a broader array of plants, there are a few immediate concerns such as Golden Bamboo (Phyllostachys aurea), Black Bamboo (Phyllostachys nigra) and Broad-Leaved Bamboo (Sasa palmata). These bamboo species are particularly a problem due to their popularity and potential for their capability to exploit weaknesses within structures, impact or dislodge hard landscape features, and most notably, lead to amenity value loss within gardens. 

The risks

Assessing the severity of invasive bamboo infestations remains a subjective topic, especially when we consider that a majority of the plant’s biomass is located below ground, where we cannot see. However, there is scope and a forthcoming necessity for a risk evaluation similar to that of Japanese Knotweed. Rather than succumbing to a narrative of hysteria, portraying bamboo as “Japanese Knotweed 2.0,” we should focus on ensure its control. Where required we could even adopt the guidance outlined within the Professional Standard for Japanese Knotweed by the Royal Institute of Chartered Surveyors (RICS). It provides us with analytical tools required to foster a reasonable approach to many more invasive plants which could affect our homes.

Addressing the challenges posed by invasive bamboo requires a combination of public awareness, regulatory measures, and practical management strategies. Raising awareness about the potential invasiveness of certain bamboo species and educating the public on proper planting and containment techniques is crucial rather than creating another taboo narrative.

Responsible gardening practices

For gardeners, responsible practices are essential in managing invasive bamboo species. Before planting bamboo, gardeners should thoroughly research the species to understand its growth habits and potential invasiveness. Implementing physical barriers, such as root barriers, or planting in suitable containers can prevent the uncontrolled spread of bamboo rhizomes.

Regular monitoring and maintenance are also crucial to detect and address any signs of spreading early on. Simple garden maintenance can normally keep these plants in check, but when it becomes too much and the plant is crossing neighbouring boundaries, or damaging hard landscaping, it’s at that point where we should consider INNP experts as they can step in to manage the situation effectively. These professionals have the knowledge and tools to contain and eradicate invasive bamboo, preventing further damage to property and the environment.

Supported by an industry of invasive non-native plant experts who have been dealing with supposedly the most invasive plant in the world for nearly 20 years, they have no problem being able to tackle invasive bamboos when they become an issue.

Conclusion

Invasive bamboo species present a growing challenge in Great Britain, mirroring the threats posed by well-known INNPs like Japanese Knotweed. While not all bamboo species are invasive, certain types can cause significant ecological and structural damage if not properly managed.

By raising awareness, implementing regulatory measures, and adopting effective management practices, we can mitigate the impact of invasive bamboos Ultimately, the responsibility lies with both gardeners and professionals to ensure that invasive bamboo species are managed appropriately. With proactive measures, informed choices, and expert intervention when needed, we can preserve the beauty and integrity of our gardens and natural habitats.

International Invasive Weed Conference

Invasive bamboos are just one of many terrestrial invasive non-native plants scattered throughout Great Britain. At the 2024 International Invasive Weed Conference at the University of Warwick on 28 November, we will delve into both terrestrial and aquatic invasive plants, exploring their impacts at regional, national, and international levels.

This event is open to a diverse group of professionals, including surveyors, developers, water companies, ecologists, and representatives from businesses, charities, non-profits, and local councils. Join us for a valuable opportunity to network, learn, and share knowledge with industry experts and peers. 

Find out more about the International Invasive Weed Conference at www.property-care.org/events.