As part of our ongoing investment in Research and Development, we’re always carrying out different experiments on Japanese knotweed to test its resilience and the effectiveness of different treatment methods.

We already knew knotweed could regrow from a tiny fragment of rhizome, or root, left in the soil, but the results from our latest experiments have surprised even us and reinforced our belief that knotweed is one of the most resilient plants around.

It is well documented that tiny fragments of knotweed rhizomes can regrow into new plants and it’s generally accepted that the smallest piece that will regrow successfully is around 0.7g, which is smaller than a one pence coin.

We decided to find out if we could successfully regrow knotweed from even smaller pieces of rhizome and also test the regenerative capability of small, thin parts of the root as well as short chunks to assess if one is more resilient than the other. So, in December 2018 we planted samples of different sizes and weights in our laboratory at our headquarters in Send, Surrey.

While the early results have been varied, after 13 days we achieved successful regrowth from a thin piece of rhizome weighing just 0.2g. We are now testing further samples at 0.2g to see if this was a particularly energy-rich part of the root which prompted these results and will update you on our findings!

Whether Japanese knotweed can successfully regrow from 0.2g of rhizome outside lab conditions remains to be seen, but it’s certainly true that treating knotweed really is a job best left to professionals. Homeowners who try to dig it out themselves are highly unlikely to find and remove every tiny particle of rhizome from the ground, meaning the knotweed will simply regrow.