Dealing With Japanese Knotweed on Rental Property in Teesside
Dealing with Japanese knotweed on a rental property in Teesside is a challenge every landlord hopes to avoid. If you've discovered it, here's what you need to know about identifying it, your legal obligations, treatment options, and how it affects property value.
What is Japanese Knotweed?
Japanese knotweed (Fallopia japonica) is a fast-growing invasive plant originally from East Asia. It's easy to underestimate how aggressive it is until you see it in action.
It spreads aggressively through underground roots called rhizomes, which can extend several metres from the visible plant and regrow year after year. Cut down the visible growth and the rhizomes remain alive underground, ready to return stronger the following season.
During spring and summer, the plant reaches three metres tall, growing several centimetres per day at peak season. Look for these markers:
- Shield-shaped leaves arranged in a zigzag pattern along the stem
- Hollow, bamboo-like stems with distinctive purple or reddish speckles
- Creamy-white flower clusters in late summer
- In winter, brown, dead canes above ground (but rhizomes stay alive underneath)
Teesside properties—especially those near the River Tees, along railway corridors, or on former industrial land—are particularly vulnerable. Knotweed thrives in disturbed ground. If you own property in TS1, TS3, TS5, or TS7, or if you notice knotweed on neighbouring land, inspect your garden boundaries regularly during the growing season.
Contact us at Ascot Knight if you need guidance on managing invasive plants or other maintenance challenges on Teesside rental properties.
Legal Obligations for Landlords
You're not legally required to remove knotweed from your land. You are legally required to prevent it from spreading to neighbouring properties.
Under the Wildlife and Countryside Act 1981, allowing knotweed to grow in the wild is an offence. The Anti-social Behaviour, Crime and Policing Act 2014 allows councils to issue a Community Protection Notice if knotweed is affecting neighbouring properties—which is a much less pleasant piece of paper to receive than rent.
As a landlord, you have additional duties:
- The Homes (Fitness for Human Habitation) Act 2018 requires you to maintain the property in a fit state. If knotweed damages the structure or creates unsafe conditions, you must address it.
- Section 11 of the Landlord and Tenant Act 1985 requires you to keep the building in repair. Structural damage caused by knotweed falls under this duty.
- When selling, you must disclose knotweed on the TA6 property information form. Failure to disclose can result in legal action from the buyer.
If you're concerned about boundary issues or neighbouring disputes, knotweed encroachment adds another legal layer. Neighbours have legal remedies if knotweed from your property spreads to theirs.
Impact on Property Value
The presence of Japanese knotweed affects property value differently depending on whether you're renting or selling.
For sales: Property values typically drop five to fifteen percent (or more in severe cases) due to knotweed. Mortgage lenders are cautious; many won't lend unless a professional treatment plan with an insurance-backed guarantee is in place. This significantly impacts saleability and can delay sales indefinitely.
For rentals: The impact is usually less dramatic. Most tenants care less about knotweed than buyers do, particularly if you're visibly managing it with professional treatment. A severe infestation that damages outdoor spaces will affect lettability, but controlled treatment is often acceptable. Transparency helps; tenants respect landlords who address problems proactively.
Mortgage and insurance implications: If refinancing, disclose knotweed to your lender. Most will require evidence of a professional treatment plan before releasing funds. Insurance-backed guarantees from treatment providers address lender concerns and protect your investment.
Treatment Options: Herbicide vs. Excavation
There are two main approaches to treating Japanese knotweed, each with different timelines and costs.
Herbicide treatment (most common) A specialist applies glyphosate-based herbicide, usually via stem injection or foliage spray. Treatment must occur during the growing season when the plant actively transports nutrients down to the rhizomes.
Herbicide treatment takes three to five years to fully eradicate the plant because the rhizome system is extensive. You'll need annual treatment visits during this period, costing approximately £1,000–£3,000 depending on infestation size. Reputable companies provide insurance-backed guarantees, which assure mortgage lenders the treatment is working and persist even if the company ceases trading.
Excavation (faster, more expensive) Physical removal of the plant and rhizomes resolves the issue in a single operation but costs £5,000–£20,000+ depending on the extent of infestation and site access. Excavated material must be disposed of at licensed facilities as controlled waste—it cannot be fly-tipped or burned on-site.
Which to choose? For most Middlesbrough landlords, herbicide treatment represents the best balance of cost and effectiveness. Excavation is best reserved for development scenarios where the multi-year timeline doesn't work, or where immediate resolution is essential.
Choosing a Treatment Provider
Hire a specialist knotweed contractor, not a general gardener or landscaper. This requires specialist knowledge, certification, and access to the right disposal routes.
Look for membership of the Property Care Association (PCA), which lists accredited knotweed specialists. Ensure the company provides an insurance-backed guarantee that satisfies mortgage lenders and persists even if the company ceases trading.
Obtain at least two quotes. A reputable contractor will conduct a proper site survey—mapping the infestation, identifying rhizome spread, and providing a clear treatment plan with estimated timeline and costs. If someone quotes over the phone without visiting, find another contractor.
Managing Knotweed With Your Tenant
If knotweed is identified during an active tenancy, communicate openly. Explain that you're aware of it, that it's being professionally managed, and that treatment is underway or planned.
Advise your tenant explicitly not to cut, mow, dig, or disturb the knotweed. Cutting without herbicide stimulates growth; digging fragments rhizomes and spreads the plant further. Tenants sometimes try to "help" by tackling an obvious problem—explain why this makes things worse.
Ensure the treatment contractor can access the property at necessary times during the growing season. If the knotweed is in the rear garden, coordinate with your tenant in advance to minimise disruption. Most tenants will cooperate if they understand why access is needed.
Knotweed on neighbouring land: You can cut back the parts crossing onto your property. Treat cut material as controlled waste. For a lasting solution, discuss joint treatment with the neighbour. Treating your side while knotweed flourishes next door is futile; the rhizomes simply re-establish. If the neighbouring property is council-owned, report it to the grounds maintenance team. Councils generally respond to invasive plant reports, though timescales can be slow.
If you're managing multiple properties across Teesside, early detection of knotweed on one property prevents it spreading to others.
Frequently Asked Questions
Q: Can I dig out the knotweed myself to save money? A: Fragments from digging regenerate as new plants. Professional excavation uses specialist equipment and safe disposal practices. Paying for professional treatment usually costs less than dealing with a worse infestation six months later.
Q: Will a mortgage lender lend if I'm treating knotweed? A: Yes, if you have a professional treatment plan with an insurance-backed guarantee. Most lenders require this before releasing funds. Disclose it upfront rather than hoping they won't notice during valuation.
Q: How long until the knotweed is completely gone? A: Herbicide treatment takes three to five years. Excavation resolves it in weeks but at much higher cost. If you need a faster timeline and budget allows, excavation is the option.
Q: Does knotweed make a property unmortgageable? A: No. Most lenders accept properties with knotweed if treatment is underway with a solid plan. Some specialist lenders will lend even on untreated knotweed if the value is high enough. Disclose it and ask your lender directly.
Q: What if the neighbour's knotweed is encroaching onto my land? A: You can cut back the parts on your property and dispose of them as controlled waste. For a lasting solution, discuss joint treatment with the neighbour. If neighbouring land is council-owned, report it to the grounds maintenance team.
Q: Does landlord insurance cover knotweed? A: Rarely. Most landlord insurance policies treat invasive plants as maintenance issues, not insurable events. Check your policy wording. Early detection through seasonal inspections is more cost-effective than relying on insurance coverage.
Q: What happens if I ignore the knotweed? A: Rhizomes spread and grow larger each year, making future treatment exponentially more expensive. Neighbours can pursue legal action. Councils can issue a Community Protection Notice. Act early; costs and stress both decrease proportionally.