Yahoo Finance Five problem plants to avoid when buying a property – and what to do if you spot them
Buying a property can be a complicated business, but there may be problems lurking in the garden which threaten to derail a purchase altogether.
Britain’s outdoor spaces are home to a number of plants which are, for various reasons, considered a bit of a menace.
So much so, that the presence of certain species can mean house sellers are forced to either spend thousands to get them removed, lose out on the price of the sale or have the deal derailed altogether.
Here, Telegraph Money reveals what to watch out for – whether you’re buying or selling a property.
What issues can plants really cause?
“Problem plants” fall broadly into two categories: non-native invasive plants, which are often covered by legislation to limit their spread, and what the Royal Horticultural Society calls “garden thugs” – plants which are available to buy from garden centres but which, given the right conditions, can run amok.
Christopher Chan, senior associate solicitor at Howells, says the key to identifying any issues is to have a thorough survey done ahead of exchanging contracts.
“These problematic plants can invalidate home insurance and cause structural damage, potentially landing you with a bill if they spread into neighbours’ gardens.
“If you find any non-native invasive species in your property and do not stop them from spreading, you could be responsible for any damage they cause and may be prosecuted.”
The cost and effort of eradicating these plants can be substantial, he warns, often requiring professional treatment and ongoing maintenance to ensure they do not return.
And even if you do manage to remove them, disposing of the waste often has to be done in a controlled environment so that it doesn’t spread further.
In all cases, the key is to know your enemy – and how much it might cost you to get rid of it.
Here are some of the most common offenders.
Japanese knotweed
Perhaps the best known problem plant, the mere mention of the words “Japanese knotweed” has the potential to strike fear into the hearts of even the most committed buyer.
Jon Barton, managing director of invasive plant experts PBA Solutions, says it is easy to spot the plant’s zig zag stems and distinctive bright green shield-shaped leaves in spring and summer.
Japanese knotweed roots, or rhizomes, are extremely good at exploiting opportunities and capable of forcing their way into cracks and weak points, and have been known to cause damage to property foundations along the way. This means it can be harder to obtain a mortgage on a property where knotweed is present.
“Once the rhizomes take hold, they form a vast network of interconnected runners that can spread several metres through the soil,” Mr Barton explained.
But all is not necessarily lost if you discover the plant on a potential property, said Paula Higgins, chief executive of the HomeOwners Alliance.
“There was a time when it was seen to be terrible, and you wouldn’t have been able to get a mortgage at all,” she said.
“Now, although there is some scaremongering, it’s accepted that it can be safely eradicated.”
Knotweed growth used to be assessed on distance from a property, regardless of its size or spread.
But guidance from the Royal Institute of Chartered Surveyors (RICS) released in 2022 requires knotweed growth to be categorised in one of four categories, from A to D.
Growth in categories A and B will mean mortgage companies require a remediation specialist’s report before releasing any money, but plants in categories C and D are not expected to affect borrowing.
Your best bet for getting rid of Japanese knotweed is to call a professional firm which will undertake a herbicide treatment plan costing around £3,000, which generally includes a 10-year insurance-backed guarantee.
Alternatively, digging out the plant completely can cost upwards of £10,000.
Sellers are legally obliged to declare the presence of any Japanese knotweed via a TA6 form so buyers should know where it may be an issue.
If this is the case, buyers could consider either trying to negotiate a price reduction, or insist that the problem is dealt with by the sellers prior to completion.
There’s no need to run a mile if it is discovered in or close to your dream home, Ms Higgins said.
“You need to ask lots of questions, do your research, and get a survey done,” she added.
“After that it depends on your appetite for risk and whether you’re willing to sort it out yourself.”
Bamboo
According to Environet, which identifies and eradicates invasive plants, around 8pc of homes in Britain have bamboo growing on the property, and a further 3-5pc have it growing next door.
While the plant is useful for privacy screening, its roots can rapidly overtake a garden, and often push up paving slabs in patios or driveways. The Telegraph has even seen one case where the plant had started growing out of someone’s oven.
Although declaring any bamboo on your property isn’t legally necessary in the UK, if it has caused a dispute with neighbours it will potentially come up as an issue during the sales process.
Environet’s research also found that 71pc people weren’t aware that bamboo could cause any damage whatsoever.
“There was such a craze for planting it around 10 or 15 years ago, and those plants are really now coming to maturity,” explained Emily Grant, director at Environet.
A common problem with bamboo is that it spreads at a shallow level, with roots which reach across rather than down.
The roots exploit cracks or gaps, potentially causing thousands of pounds worth of damage if it disrupts foundations or services.
“You can imagine that it pops up not only in your garden, in places you didn’t want it to, but on a neighbour’s property too,” Ms Grant said.
As with most things, the earlier it is dealt with, the better.
“Removing it starts from about £3,500, but we are increasingly seeing the cost run into tens of thousands because people have ignored it,” she added.
If you are a buyer, it is worth asking when the bamboo was planted to get a sense of any potential spread and establish whether it has ever been seen on neighbouring land.
With potentially huge cost implications, asking for a reduction in the selling price or for the sellers to carry out remedial work might be appropriate.
Rhododendron
Often associated with grand estates, rhododendrons are mainly problematic because they can become enormous.
Mr Barton said: “They outcompete other vegetation for light, nutrients and space, often spreading unchecked.
“They thrive in acid soils, where certain species can create hostile environments for neighbouring plants once established. The leaf litter is extensive and slow to decompose, contributing to a large biomass layer that hinders seedling growth.”
On top of that, rhododendrons produce grayanotoxins, particularly in their younger leaves. Contact with the plant can cause skin irritation for some people and all parts of the plant are poisonous for dogs to ingest.
A good surveyor should flag these as a potential issue up front, although unlike some other problem plants, rhododendrons don’t pose a threat to buildings, and therefore any negotiations from a buyer’s point of view could be limited unless it is clear that the plant needs to be completely removed.
This can be difficult, Mr Barton said, and usually requires a specialist tree surgeon to ensure that no rhododendron material remains viable, costing around £1,000 for a small infestation.
“With all these things, it is worth talking to neighbours before you take action,” said Ms Higgins. “It’s a very emotive topic.”
Buddleia
Even a relatively small buddleia is capable of producing more than one million seeds a year which are able to establish new small plants in inhospitable places such as walls, bridges and chimney stacks.
Once established, buddleia forms substantial woody plants that can be very difficult to remove, not least because they can be at height.
A study by Centre for Agriculture and Bioscience International (CABI) in 2010 estimated that more than £960,000 was spent in Britain each year undoing damage or problems caused by buddleia growing in the wrong place.
“The cost of remediation increases when access is restricted and specialist equipment is needed to work at height,” said Mr Barton.
“A typical treatment plan for a single bush within a wall accessed using ladders will cost between £1,500 and £3,000, and the plan will involve repeat visits.”
If you’re thinking of buying a property with buddleia present, you may consider having a thorough survey of the building done to ensure there are no shoots in undesirable places.
English ivy (also known as common ivy)
“If you’re buying a property and it is covered by something like ivy, or any other self-supporting plant, then we would definitely recommend that you get a surveyor’s opinion on the likelihood that it could cause damage,” said Ms Grant.
Ivy’s aerial roots allow it to spread rapidly over a building, wall, fence or tree, penetrating small cracks and exploiting weaknesses in structures.
This could affect your ability to insure a property, or risk invalidating your insurance if damage occurs unexpectedly.
“Having the foliage trapped against a building for a prolonged period can create damp problems, which further the structural decay,” said Mr Barton.
He added that homeowners could handle some ivy remediation tasks themselves but for professional herbicide treatments using industrial-grade chemicals you’ll need to use trained technicians. For this you should expect to pay around £160 per treatment.
For more extensive removal of climbers like ivy which have covered a single face of a typical semi-detached house you should expect to pay between £3,000 and £5,000.
Although it might look characterful on a house, buying a property covered in ivy could land you with a hefty bill – something that is worth discussing with the seller during negotiations.
