Cost guide
How much does japanese knotweed cost?
Method and infestation area drive the figure, and the gap between the two main routes is enormous. Herbicide on a stand under 50 square metres runs £1,500 to £3,000, while full excavation and off site disposal on the same plot runs £4,000 to £20,000. Published UK averages across all jobs sit near £6,150.
Typical prices
Ranges, not quotes. A quote depends on your room.
| Work | Typical UK price |
|---|---|
| Specialist survey and identification | £250 to £800 |
| Herbicide programme, under 50 square metres | £1,500 to £3,000 |
| Herbicide programme, 50 to 100 square metres | £3,000 to £5,000 |
| Excavation with root barriers | £2,000 to £10,000 |
| Cell burial or on site relocation | £3,000 to £15,000 |
| Full excavation and off site disposal | £4,000 to £20,000 |
Insurance backed guarantee pricing is quoted several ways, from £75 added to a treatment plan up to a percentage of contract value on jobs above £5,000. Standalone management plans are not priced publicly by any specialist checked.
What moves the price
- Area of the stand. Under 50 square metres against 100 to 499 square metres roughly triples every method.
- Method. Herbicide at £20 to £60 a square metre against full excavation at £100 to £400.
- Landfill. Contaminated soil disposal at £50 to £200 a tonne including transport.
- Barriers. Root barrier membrane at about £6 a square metre, with trenching from £120 a metre at shallow depth.
- Guarantee. Insurance backed guarantees run £75 to £750 depending on contract value and term.
Worth knowing
Planting Japanese knotweed or otherwise causing it to grow in the wild is an offence carrying an unlimited fine and up to two years in prison on indictment.
Wildlife and Countryside Act 1981, section 14(2) and Schedule 9
Who quotes for it
Questions about japanese knotweed
How long does herbicide treatment take?
Government guidance puts it at a minimum of three years, and most plans run three to five with monitoring afterwards. Regrowth from dormant rhizome is normal in year two and does not mean the programme has failed.
Can a householder treat it themselves?
Government guidance advises against it without the right skills, and anyone spraying has to hold a certificate of competence or be directly supervised by a holder. Cut canes and contaminated soil also count as controlled waste on removal.