Japanese knotweed help

V2001

Ok so my dream bungalowi want to purchase has knotweed which has spread from the neighbours garden into this house.
They are 2 years into a 5 year guaranteed plan in place.

My question is with herbicide treatment does it ever go away permanently? Or with treatment does it come back after a few years and can regrow?

Where its growing I would want to do a extension over that area. Is it to risky incase it grows under the extension in future?

V2001

Also at the back of the garden is this hedge which looks like bamboo(at bottom of pic). Is it bamboo? Sorry for bad pic but only one I have..

daveyjp

Photo isnt great but I cant see any knotweed on that photo.

However if it is close it won't go away unless dealt with properly.

V2001

No in the photo I'm referring to the bottom of the pics. Does those plants look like bamboo?

twoLou

V2001 said:

No in the photo I'm referring to the bottom of the pics. Does those plants look like bamboo?

It looks like Bamboo to me and the invasive type too so will be problematic to remove.

I can’t help you with the Knotweed as know nothing about it but best of luck what ever you decide to do.

Freecall

Japanese knotweed can certainly be treated effectively.  You may get some return but conventional weedkiller will deal with it.

The bamboo though is the problem, much more difficult to get rid of.

Dustyevsky

V2001 said:

They are 2 years into a 5 year guaranteed plan in place.

My question is with herbicide treatment does it ever go away permanently? Or with treatment does it come back after a few years and can regrow?

If the treatment plan is insurance-backed, it's likely to be with a reputable company and the chances of re-growth will be low. Anyway, it's not a triffid, and the horror stories of the red tops need to be viewed with a good pinch of salt. It will not grow through the foundations and floors of a properly constructed extension.

The bamboo is likely to be of the non-clumping type and these sorts do spread, but again, weedkiller, properly applied, ought to sort it out in the long term. If you're doing an extension, use the digger to get it out! I have only killed the low growing spreading bamboo with a herbicide applied in early autumn, but it didn't return. It's a job most amateurs could do with a careful approach: https://www.progreen.co.uk/problem/bamboo