Every year we carry out a consumer survey with YouGov to explore awareness of invasive plants and consumer attitudes towards them.

The key findings of our 2022 survey of over 2,000 people are:

• Awareness of Japanese knotweed among the public continues to grow – now 82% compared to 77% in 2021 – meaning buyers are better-informed of the risks
• Awareness is considerably lower in younger age groups, with just 42% of 18 – 24 year-olds having heard of knotweed compared to 81% of 35 – 44 year-olds and 96% of over 55s
• 59% of respondents would be uncomfortable buying a property that had been herbicide treated for a knotweed infestation, compared to 29% of people who would be uncomfortable buying a property with knotweed where the plant had been excavated from the ground.
• If knotweed was discovered after moving into a property, more than three quarters (77%) of people would be concerned
• The main reasons for concern are: the cost of treatment/removal (selected by 81% of respondents), damage to property and gardens (77%), problems selling in the future (69%), the potential impact on the property’s value (65%), and the risk of the plant spreading to a neighbouring property (49%)
• Worryingly, 28% of people who stated they wouldn’t be concerned to discover knotweed on a property after they had bought it, believe they can treat the problem themselves

What’s the main takeaway?

RICS has relaxed its guidance to encourage herbicide-based methods of dealing with knotweed, which aim to control the plant rather than eradicate it. But our survey shows that buyers would be far less comfortable buying a home where knotweed has been herbicide treated, which leaves a high chance that the plant is still present and induced into dormancy.

The best way to preserve your property’s value and make it easier to sell in the future is to professionally excavate knotweed from the ground, secure a 10-year insurance-backed guarantee and be honest and up-front with potential buyers.