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Japanese Knotweed in Hampshire

A comprehensive Japanese knotweed risk assessment for Hampshire in the South East region — covering local risk factors, affected areas, and practical advice for homeowners, buyers, and sellers.

Knotweed Risk in Hampshire

Hampshire has moderate knotweed risk focused along the Test and Itchen river valleys, the Basingstoke Canal, and railway lines serving Southampton and Portsmouth. Victorian-era naval housing in Portsmouth and Gosport has localised infestations, and the M3/M27 corridor construction disturbed contaminated soils during the 1970s.

What to Do If You Find Knotweed in Hampshire

If you discover or suspect Japanese knotweed on a property in Hampshire:

  1. Don't disturb it — Cutting, mowing, or digging can fragment rhizomes and worsen the infestation
  2. Get a professional survey — A PCA-accredited surveyor will confirm identification, categorise the infestation, and recommend treatment
  3. Start treatment promptly — Early intervention limits spread and reduces long-term costs
  4. Obtain an insurance-backed guarantee — Essential for property transactions and mortgage applications
  5. Know your legal obligations — You must prevent knotweed from spreading to neighbouring properties

If you're buying in Hampshire

Properties in Hampshire should be checked for knotweed as part of the buying process. A standard homebuyer's survey may note knotweed but won't provide the specialist assessment needed for mortgage approval. Commission a dedicated knotweed survey alongside your standard survey.

If you're selling a property in Hampshire and know about knotweed, proactive treatment and documentation will help your sale proceed smoothly.

Areas in Hampshire

Browse knotweed information for specific areas within Hampshire:

Southampton

SO14, SO15, SO16, SO17, SO18, SO19

Portsmouth

PO1, PO2, PO3, PO4, PO5, PO6

Winchester

SO22, SO23

Basingstoke

RG21, RG22, RG23, RG24, RG25

Frequently Asked Questions

How common is Japanese knotweed in Hampshire?
Hampshire has moderate knotweed risk focused along the Test and Itchen river valleys, the Basingstoke Canal, and railway lines serving Southampton and Portsmouth. Victorian-era naval housing in Portsmouth and Gosport has localised infestations, and the M3/M27 corridor construction disturbed contaminated soils during the 1970s.
Should I get a knotweed survey when buying in Hampshire?
If you're buying a property in Hampshire, a specialist knotweed survey is recommended — particularly for older properties, those near waterways or railway lines, and any property where the seller has indicated knotweed on the TA6 form. A PCA-accredited surveyor familiar with Hampshire will understand local risk factors and can provide a RICS-compatible report for your mortgage lender.
How much does knotweed treatment cost in Hampshire?
Treatment costs in Hampshire are broadly in line with national averages: £2,000–£5,000 for herbicide programmes and £10,000–£50,000+ for excavation. Costs may be slightly lower in high-density areas where treatment companies are more established and competitive. Always get at least two quotes from PCA-accredited companies.
Can I get a mortgage on a property with knotweed in Hampshire?
Yes, most mainstream lenders will approve mortgages on Hampshire properties with knotweed, provided a treatment plan and insurance-backed guarantee are in place. The RICS management category assigned by your surveyor determines which lenders will proceed. See our mortgage guide for lender-specific policies.