When viewing a property your main concerns are probably going to be things like the condition of the roof, how old the wiring is and how you’ll decorate when you move in. But don’t forget the outside spaces.
Some species of plants should ring alarm bells when spotted at a property as they can mean structural damage, and even prosecution for the owner if left unchecked. You may want to think twice about purchasing a house with rife with one of these photosynthesising pests, or at least request the current owner sorts the problem before you get the keys.
But, how do you know if your dream property is home to one of these dreaded plants? We’ve put together a quick guide to identifying six of the main garden villains and what their presence could mean for their unlucky owner.
Six problem plants at a glance
| Plant | Can it damage a property? | Will mortgage lenders be concerned about it? | Is it illegal to plant it myself? | Will I need professional help to get rid of it? |
| Japanese knotweed | Yes | Yes | Yes | Yes |
| Bamboo | Yes | Maybe | No | Yes |
| Oak, poplar & willow trees | Yes | Maybe | No | Yes |
| Giant hogweed | No | Maybe | Yes | Maybe |
| Himalayan balsam | No | Maybe | Yes | Maybe |
| English & common ivy | Yes | Maybe | No | Maybe |
1. Japanese knotweed
Most people have heard of Japanese knotweed and know it’s an invasive pest they want nothing to do with. There’s good reason for this terrible reputation!
Japanese knotweed is a bamboo-like plant that can grow up to 10cm per day and will force its way into cracks. It can destroy tarmac, brickwork, drainage pipes and even foundations of buildings, and it’s notoriously difficult to get rid of.
Laws
- You must not plant Japanese knotweed
- Nor should you allow it to grow in the wild
- Although you don’t have to declare its presence on your property, you may be sued if it spreads to a neighbour’s property
Mortgages and Japanese knotweed
If a property has Japanese knotweed, it may be devalued up to 15%. Mortgage lenders may also be unlikely to approve an application.
Identification and removal
- Quick-growing, bamboo-like structure
- Purple-speckled stems
- White flowers
Removing Japanese knotweed can be difficult, expensive and time-consuming. Using a specialist company that is a member of the Invasive Non-Native Specialists Association is a good idea, as is obtaining a treatment certificate to appease mortgage lenders.
2. Bamboo
Similar to Japanese knotweed, bamboo spreads extremely easily and can become a nuisance in a very short space of time. Some running bamboo varieties send out long, horizontal rhizomes up to 30ft which can not only spread the plant to neighbouring property, but cause structural damage to bricks, tarmac and foundations.
Laws
Although it’s not classified as invasive and you’re welcome to plant it, it’s possible a neighbour could take legal action if it spreads to their land.
Mortgages and bamboo
As it’s not classified as invasive, you shouldn’t have a problem trying to get a mortgage for a property with bamboo. However, this may not always be the case as issues with bamboo are become more prevalent.
Identification and removal
Bamboo spreads through a rhizome system and there are two main types; clumping bamboo stays in a large root ball while running bamboo shoots out long rhizomes. The latter is of most concern for the damage it can cause.
Identifying the exact type of bamboo can be tricky but if you dig down and find a root ball, it is most likely clumping bamboo and you can breathe a sigh of relief. If you find long root systems spreading out, you may have a problem.
Asking a professional for accurate identification and removal is the very best way of dealing with concerning bamboo at a property.
3. Oak, poplar & willow trees
Although we all love trees, we don’t necessarily want them on our property. Large trees can be a problem for many reasons including drawing water from the ground, shrinking the soil and causing subsidence. Roots can also cause issues, spreading out and breaking through concrete, pipes and tarmac. Oak, poplar and willow trees are the main rouges in this department. Trees at a boundary can also cause damage to neighbouring property not to mention quarrels between residents.
Laws
Before chopping down certain trees, you must check to see if they have a TPO (Tree Preservation Order). If they haven’t then you may go ahead and fell them. However, if they have, you must apply for permission from the local council to get rid of them.
Mortgages and trees
While the presence of oak, poplar and willow trees does not necessarily spell doom for your mortgage hopes, if you have one of these trees in a problematic location, you may run into issues with your application. If there’s already subsidence damage, your lender will certainly be concerned and reluctant to lend any money.
Identification and removal
- Oak: lobed, symmetrical leaves; acorns; thick tree trunk up to 21m high
- Poplar: Lombardy poplar can be up over 30m high; diamond leaves; vertical branches.
- Willow: usually found near water; narrow leaves on hanging vines, 5-10cm long
If a tree is large enough or in a position to be causing problems then you really should get a professional tree surgeon to help. It’s also a good idea to get a structural engineer to check that removing the tree won’t lead to heave, when soil swells and causes structural damage.
4. Giant hogweed
Giant hogweed is a dreaded plant not because it damages property but because it can be harmful to humans. This invasive plant is often found along riverbanks where its seeds are transported by water, but keep a wary eye out wherever you are.
It’s the sap that’s the real villain when it comes to giant hogweed. If it comes into contact with your skin it causes long-lasting photosensitivity leading it to burn, blister, pigment and scar.
Laws
- You must not plant or intentionally grow it
- You must not import, transport or release it to the environment
- It must be disposed of in licensed landfill sites
Mortgages and giant hogweed
Your mortgage lender may or may not be concerned by the presence of giant hogweed. If it’s deemed a serious problem and likely to affect what buyers are willing to pay for the property, you may run into problems.
Identification and removal
Giant hogweed is extremely similar in appearance to cow parsley with long stems and clusters of attractive, small white flowers. However, it is generally larger, growing up to 5m tall. The stems are green with purple spots and small white hairs, and the leaves resemble rhubarb leaves.
It’s possible to take care of removing giant hogweed yourself but be extremely careful to cover all your skin and eyes. You’ll need to keep an eye on the place it was growing for several years to ensure it doesn’t make a comeback and remember to destroy the waste properly: either by burning or in licensed landfill.
If in doubt, ask a specialist to take care of this nasty, invasive plant for you.
5. Himalayan balsam
Himalayan balsam, like giant hogweed, is another plant which won’t damage buildings but can affect saleability of a home. This pretty plant grows up to 3m high with clusters of purple/pink helmet-shaped flowers in June-October. It spreads rapidly and, while bees and pollinators love it, gardeners loathe it!
The reason this non-native plant is disliked so much is because of its ability to quickly take over areas, successfully competing with native plants for space, light, pollinators and nutrients.
Laws
While you mustn’t encourage the growth of Himalayan balsam, you’re not obliged to remove it. However, if it spreads to a neighbour’s property they might consider suing you.
Mortgages and Himalayan balsam
Unlike Japanese knotweed, Himalayan balsam isn’t a plant that your mortgage lender will be enormously worried about. However, if it really has taken over and will affect how much the property could fetch, then they may be reluctant to lend.
Identification and removal
- Grows up to 3m high
- Clusters of purple/pink helmet-shaped flowers in June-October
- Flowers are followed by seed pods that explosively open when ripe, spreading vast quantities of seeds
While you may choose to get a professional to thoroughly remove this irritating plant, you can take care of it yourself if you choose. If so, cut it below the lowest node/shoot and pull it up as it grows. The seeds can survive multiple years so keep an eye on the area to ensure you really get on top of the problem.
6. English & common ivy
Everyone is familiar with English ivy and many think of it as very attractive. Indeed, it is intentionally grown for decorative purposes in gardens across the country.
However, if this self-clinging climber grows on a building, it can penetrate and expand cracks, lift roof tiles and damage guttering.
Laws
Something to consider when removing ivy is that it is an offense to damage/destroy wild birds’ nests while they are in use or being built. Plenty of birds will love to build a cosy home in ivy so make sure you check before getting the shears out.
Mortgages and ivy
Mortgage lenders are unlikely to be too worried about ivy unless it’s climbed up to the loft space. In this case, they may be unwilling to approve your mortgage/request it’s sorted beforehand.
Identification and removal
- Green/light grey, heart-shaped, waxy leaves
- Dark berries
- English ivy resembles Virginia creepers from a distance
You can often pull ivy down by hand but be careful not to pull any of the building with it! Remember to also kill the roots in the ground/brickwork with weed killer.
Get in touch
Needless to say, you want to know if any of the above plants are growing at a property you’re interested in and we’re here to help. Our team of Chartered Surveyors have decades of experience identifying these problematic plants and will give advice on next steps if they’re discovered during a house survey. Please get in touch to find out more.