For solicitor Rodger Burnett, it should have been one of the proudest days of his life. After years of study and saving, the 36-year-old had finally got his foot on the property ladder — albeit with a hefty mortgage on the £400,000 property.
Previously let to students, the mid-terrace house in Camberwell, South London, needed some love and attention. But to Rodger, it was already home — and it had the added bonus of a small garden backing on to a railway line.
A couple of weeks after he moved in during the spring of 2012, he invited his mother to see the house and help him with the decorating. Her reaction came as a shock. ‘Mum walked into the kitchen, took one look out of the window and started yelling that I was an idiot,’ he remembers with a wince. ‘She kept saying I’d wasted all my money.’
A new report from researchers at Leeds University working with the U.S. infrastructure services company AECOM has questioned Japanese knotweed’s fearsome reputation
The cause of her dismay was looming over the garden wall — 12ft high with thick stems of bamboo-like cane and a dense leafy crown — Japanese knotweed, the ninja killer of the gardening world.
Seemingly indestructible, spreading like plague and able to burrow into the foundations of buildings, the plant is widely regarded as the horticultural equivalent of a virulent cancer. Or is it? A new report from researchers at Leeds University working with the U.S. infrastructure services company AECOM has questioned Japanese knotweed’s fearsome reputation, prompting headlines that it was ‘no more dangerous than buddleia’.
The Leeds study found it cannot ‘grow through’ brick or concrete despite popular misconception, and is less likely to damage underground drains than tree roots.
So which is it — the bane of the British property market on the back of which a lucrative eradication industry has established itself, or a harmless plant that we should grow to love and even cultivate because it is also a delicious rhubarb-like vegetable, rich in vitamin A and antioxidants?
Making the most of the nutritious benefits of the knotweed running riot in his garden wasn’t the first priority for Rodger Burnett that April day six years ago.
He remembers a cold feeling of fear in the pit of his stomach at his mother’s reaction that got worse as he combed the internet for information. ‘I discovered one horror story after another,’ he says.
When he’d first viewed the house the previous November, there had been no sign of it — knotweed dies back in winter. Now it was rampant, and it was clear it had spread to his garden from the railway embankment where it was also flourishing.
‘It was shooting up about three or four inches every day,’ he says.
He learned knotweed’s presence would have a catastrophic effect on the property’s value. Mortgage lenders are reluctant to approve loans on houses with knotweed in the area, so it becomes difficult to sell.
Adding to his woes was the fact that it would cost thousands of pounds to call in specialist firms to clear it and he would still have to declare the problem to any future buyers.
Mr Burnett decided his best recourse was to use his legal training and bring a ‘private nuisance’ case against the owners of the railway embankment, Network Rail.
He had a battle on his hands. The railway bosses were loath to admit responsibility, he realised, because many other properties could be affected — perhaps tens of thousands. ‘They fought it tooth and nail, but eventually settled,’ he explains.
A pest eradication expert poisons Japanese knotweed in Cornwall
The experience inspired Mr Burnett to set up his own legal practice, Charles Lyndon in Moorgate, London, partly specialising in knotweed complaints. One of his most distressing cases, involving ex-builder Robin Waistell, was finally settled this month, after a four-year battle with Network Rail.
In 2017, Mr Waistell and a neighbour Stephen Williams, from Maesteg in South Wales, were awarded £15,000 each in compensation after the ‘pernicious weed’ spread from the nearby railway under their homes.
Network Rail appealed but, as the Mail reported this month, the Court of Appeal ruled compensation was justified, raising the prospect of an avalanche of similar claims.
For Mr Waistell, there is little cause for celebration. The 71-year-old retired widower is desperately ill with motor neurone disease. Next month he plans to leave his two-bedroom bungalow and move into a respite home.
Before his diagnosis, he’d dreamed of selling up and seeing out his days in Spain, but that became impossible because of Japanese knotweed.
The plant sends out rhizomes, or burrowing tendrils, that search incessantly for water and nutrients
His back garden is a dense jungle, with plots of knotweed thick as scaffolding that blot out the sky. In botanic jargon, the plant is ‘mono-dominant’, taking over its environment, preventing light from reaching other, smaller plants. As an alien species, it is of no interest to our native butterflies and other insects, which cannot feed on it. Even birds dislike nesting in it.
Mr Waistell is in no fit state to attack his knotweed invasion with saw and secateurs. But even if he were, there is little he could legally do.
Japanese knotweed is classed as ‘controlled waste’ — waste that is subject to legislative control in either its handling or its disposal because of health, environmental or other risks.
He could not simply cut it down and dispose of it in the recycling bin — that would be breaking the law. And even if he took it to a licensed landfill site, to be securely incinerated and buried so that no spores could escape, he would face hefty fees.
In any case, the job would have to be done repeatedly throughout the summer: cut down one knotweed stem and another shoot pops up overnight in its place.
Every time the plant was hacked down, all the parts would have to be burned. Even a fragment of knotweed left on the ground or in a compost heap can take hold.
And all that work would barely begin to address what is claimed to be the real problem. Though the stems were slashed back, the dense roots would remain in the ground. And it’s here that knotweed is believed to be most pernicious.
The plant sends out rhizomes, or burrowing tendrils, that search incessantly for water and nutrients. They burrow their way into the smallest crack and expand. As they grow thicker, the claim is that they slowly prise apart walls and foundations.
Treating the plant with repeated doses of weedkiller might appear to destroy it — but in reality the rhizomes might simply be dormant. They will lie inert, until disturbed by digging and then, zombie-like, they begin burrowing again.
That’s why, even if homeowners call in specialist firms to eradicate knotweed, at a cost of up to £15,000, the past infestation still has to be disclosed to future buyers. They might want to build an extension, or landscape the garden — and that risks retriggering the knotweed. Result: a catastrophic price crash.
Mr Waistell fears he will struggle to get more than half the value of his £130,000 bungalow and that’s money he may need for his future care.
His is a bitter victory over Network Rail. ‘I’ve taken them on with my money, and they fought back with public money,’ he says. ‘They don’t care as long as they get their fat pensions at the end of the day.
‘They’ve spent hundreds of thousands fighting this — money that could have been used to treat knotweed along many miles of railway embankments.’
Now he wants to turn his back on the whole disastrous business. ‘My son is coming next week, he can have what he wants from the place. Then I’m putting it up for sale. I won’t get the market value, so I’ll just have to get what I can.
‘The doctors say if I’m lucky I might have another year or two. I don’t want to spend it here, surrounded by this stuff.’
When you understand where Japanese knotweed first flourished, its incredible hardiness starts to make sense. It was discovered by German physician and botanist Philipp von Siebold in the early 19th century, growing in volcanic fissures near the city of Nagasaki.
Despite rivers of blistering lava and poisonous gases, it thrived thanks to its underground network of rhizomes. Von Siebold dubbed it Fallopia japonica, or Japanese tubes. It quickly earned the name knotweed because of the knuckle-like joints along its stem.
In the 1830s, then living in Holland, he began selling cuttings all over Europe. As an ornamental plant it was much in demand, and a gift of knotweed sent to Kew Gardens is thought to be the source of most of the Fallopia japonica in Britain.
But it was South Wales that felt its impact first. By 1886, a curator at Cardiff Museum noted that Japanese knotweed was ‘very abundant’ in Maesteg, while in nearby Swansea, children called it ‘peashoots’ — because the hollow stems made perfect peashooters.
The spread was helped by some railway companies, which appear to have had an unofficial policy of planting it on embankments because its dense roots were believed to be good at preventing landslips on to the tracks, and the thick summer foliage could offer trackside houses some privacy from passing trains, as well as soaking up noise and smoke.
What the railway bosses didn’t understand was that, once planted, the weed was uncontrollable.
Its growth was encouraged along river banks, too. Trees and thick bushes help soak up water after heavy rain and prevent flooding.
But Japanese knotweed thrives at the wrong time. It’s tall in summer, when water levels are low, and dies back in winter, leaving the banks exposed.
The plant that could withstand boiling magma on the slopes of Mount Fuji was worse than useless beside the Taff or the Tawe.
Given what we know about knotweed, its history and status as the No. 1 enemy of British gardeners and homeowners, what is the truth behind those headlines suggesting the plant is much maligned?
Dr Karen Bacon, of the University of Leeds School of Geography and co-author of the controversial report with the American infrastructure firm Aecom, explains.
‘We wanted to test the idea that Japanese knotweed can cause structural damage,’ she says. ‘People say it can grow through concrete, so we went through the literature for evidence of actual damage and didn’t find much.’
Dr Bacon and her colleagues then sent questionnaires to 51 contractors and 71 surveyors who reported back on 122 knotweed-infested properties. The team also carried out their own survey on a street of 68 abandoned houses in a North of England town.
Built around 1900, knotweed was rampant in, around and under these brick buildings — ‘a worst-case scenario,’ says Dr Bacon.
‘We found it can exacerbate existing damage. We didn’t find evidence to say it can cause it. The rhizomes can’t grow through concrete, but they can grow through cracks and make things worse. They are foraging organs, travelling along the path of least resistance to find nutrients and water.’
She is, she says, alarmed by the claims now being made by some foodies that knotweed should be cultivated and rebranded as a culinary treat, its stems like tender rhubarb while the leaves, steamed or baked, a tasty vegetable that can be made into chutney.
Better still, it is claimed, the plant is rich in resveratrol, the same chemical present in red wine that helps lower cholesterol and stave off heart attacks.
‘It is highly invasive,’ Dr Bacon warns. ‘The last thing we want is for it to spread. It’s a problematic species for biodiversity. Don’t pick it and risk spreading it.’
Solicitor Rodger Burnett is unperturbed by the Leeds study.
He believes the findings confirm what many people already knew. ‘We never thought knotweed could grow through stone. But wherever there is a crack — for instance, between slabs of concrete — it will find them.
‘I’ve seen clients with knotweed growing up through their garage floors. It can pull down garden walls. One couple even had it coming up in their living room.’
So if you can’t chop it down and stick it in the recycling, and you can’t trust it to stay dead even when it has been liberally dosed with herbicide, and you don’t have £15,000 to hand to have it eradicated professionally, what can be done with this noxious nuisance from Nagasaki?
One gardener came up with his own solution. Alex Scott of Dedham was alarmed to discover Japanese knotweed growing on wasteland beside his Essex home, 20 years ago.
He dealt with it ruthlessly — snipping off the top of each stem and funnelling bleach into every hollow reed.
After repeated applications, the knotweed withered and never grew back. ‘Demise of unwelcome inhabitant,’ Mr Scott declared at the time.
Whether it is truly dead, of course, is another question.