As we approach summer, it’s worth taking a look at your garden – it turns out that some plants can not only damage your property, but also devalue it!
To help you better identify invasive plants, experts have uncovered five of the most common garden plants that can cause your property to be worth up to 15 percent less.
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Stokemont.com surveyors have also shared tips on how to identify and remove these plants.
Here are the five plants you need to know…
1. Japanese Knotweed
Removal Difficulty: High
Japanese knotweed is an invasive plant with bamboo-like red shoots and shovel-shaped leaves.
It can grow up to three meters high in spring and summer and its roots reach up to 20 meters underground.


According to Stokemont, underground spread of Japanese knotweed could disrupt pipes and drains and weaken building foundations or pavement, leading to collapse of foundations and poor flood defenses.
Because of this damage, Japanese knotweed is listed by RICS Homebuyer Reports as a property defect, with the potential to reduce the price of your property by 5 to 15 per cent.
With an average of 2,500 Google searches per month for ‘how to get rid of Japanese knotweed’, Stokemont’s Bradley advises: ‘It’s really important to check this closely and take immediate and thorough eradication action before it’s too late.
“We would strongly recommend that you seek professional help when removing them as they easily recover from even the smallest remnants.
“If you prefer to do it yourself, pesticides would be the most effective way to kill these zombie-like plants.”
2. Ivy
Removal Difficulty: Low

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English ivy is widespread throughout Europe and dangerous for your home.
With a strong wall-climbing ability, this garden invader can easily enter your wall cracks, damaging the grout and bringing moisture or leaks into the house.
Bradley advised: “Unlike giant hogweed, English ivy can be removed with bare hands by gently peeling it off the wall.
“You can also kill them by cutting off their roots and letting them dry out.
“However, not all wall-climbing plants are harmful, e.g. B. Boston Ivy, so we recommend consulting a professional before accidentally pruning some beautiful and safe plants from your wall.”
3. Giant Bear Claw
Removal Difficulty: High

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Similar to the Japanese knotweed, the giant hogweed is invasive with its ability to spread quickly.
Easier to spot in June and July, this cow parsley-like plant has thick green stems with purple spots and white flowers shaped like a round umbrella.
The plant, which can grow up to 15 feet tall with plate-sized flower heads, can cause blindness if the sap gets in your eyes.
Bradley said: “Widely available across the UK, especially around rivers and ponds, its sap is phototoxic and can cause severe skin burns or scarring when exposed to sunlight.
“While buyers are not causing direct damage to the property, they can still refuse to pay a higher price, if any, as the removal costs are high – up to £15,000.”
4. Poplars, willows and oaks
Removal Difficulty: Medium

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While most trees won’t cause any damage, large trees like cottonwood, willow, and oak can be dangerous if they grow near the property.
Its root systems, shallow and fast-growing, can spread up to 40 meters and absorb 1,000 liters of water and nutrients from the soil.
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Bradley added: “They could live to be around 50 years old and are harder to remove as their roots get thicker and bigger over time.
“Age, soil type, location and depth all matter when determining whether your tree is a problem.
“If grown too close to your property, they could introduce further risks of cracking in foundations, subsidence and other structural defects that could potentially cost you £5,000 to £25,000 to repair.”
5. Himalayan Balm
Removal Difficulty: Low

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As the name suggests, Himalayan balm originated in the Himalayas and was brought to Britain in 1839.
It grows up to two to three meters high and has pink flowers in summer and early autumn.
Despite its beautiful colors, this invasive plant could seed 800 meters away or even be spread through rivers, potentially killing other plants and reducing biodiversity by stealing light, nutrients or water.


While many people question whether this non-native plant is poisonous, Bradley commented, “It poses no physical danger to humans, but its significant ecological impact on nature and associated laws are not favored by buyers.”
“It is therefore recommended that you control or eradicate this plant and ensure it does not spread to your neighbors’ home as it may be illegal.”
ESTIMATED REMOVAL COST FOR EACH INSTALLATION:
- Japanese knotweed – up to £15,000
- ivy – up to £1,000
- Giant Bear Claw – up to £15,000
- trees – up to £3,000
- Himalayan Balm – up to £2,000
Note: It is illegal to put Japanese Knotweed, Giant Hogweed or Himalayan Balsam in regular yard waste (as it is a violation of the Environmental Protection Act 1990). So please consult a professional if you are unsure of the removal.