Getting rid of Japanese Knotweed
Our Environment Agency permit makes it very clear that we can’t accept Japanese Knotweed or any of the other really invasive species.
So what can you do if you find it in a garden you are working on?
Japanese Knotweed can be a nightmare. It can reduce the price of a house by tens of thousands of pounds due to its ability to grow under fences, damage paths and patios and even work its way inside cavity walls.
If there is a major infestation or the owners plan to sell the house in the next five years, contact a specialist.
Most mortgage companies want a firm associated with the trade body the Property Care Association, so check its website to find a member near you.
However, if you have only a small clump and the owners don’t plan on moving any time soon, you could aim to get rid of it yourself, says RHS chief horticultural adviser Guy Barter. “It’s evil stuff. It’s a lot of work and not feasible if there’s a vast infestation, but you can dig it out with a spade.
Because it’s classified as ‘controlled waste’, you can’t let any plant material leave the garden. So stack it up to dry on plastic or concrete and then burn it. Or put it in rubble bags and leave it to die for a few years to be sure.”
Barter suggests combining digging up the plant with a herbicide such as Roundup. And if knotweed is coming in from a neighbouring garden, he says to dig a deep trench on the boundary and line it with a strong root barrier.