Applying salt to an unwanted plant can cause the plant to dehydrate and ultimately die. … It takes a lot to eradicate this invasive species once and for all – a mere sprinkling of salt just won’t do it! Even if you pull the knotweed out of the ground and salt the soil, the plant will probably grow back sooner or later.

Will salt and vinegar kill Japanese knotweed?

There is no scientifically backed evidence to suggest that vinegar will kill Japanese knotweed. Although there has been some amateur research [6] conducted on the topic, the use of vinegar to kill or control Japanese knotweed is not recommended by any governmental guidance or professionally accredited firm.

What is the best way to kill knotweed?

A glyphosate-based weedkiller is the best option here, though bear in mind it can take several applications, over up to four seasons, to completely eradicate Japanese knotweed. It’s best applied to cut canes so the weedkiller can thoroughly penetrate the plant and roots.