There are over a million homes in the UK affected by Japanese knotweed. Having this weed in your garden could devalue your property or cause the sale to be delayed or fall through, due to misinformation or fears of what the knotweed might do. So it's good to know the facts and what you can do to remedy the problem. When selling your home you'll need to declare the Knotweed and provide a management plan of what you are doing to eradicate the problem.