How to Spot Japanese Knotweed Early Growth

Japanese Knotweed | 06th April 2020

So here we are. I’m writing this blog from home, which is a novel experience for me. I’m not used to it and it feels weird. My kids aren’t used to it either and suddenly it seems I have become the main attraction. Forget the iPad, forget YouTube and the endless hours of cartoons that can be streamed on Amazon… Dad’s home and trying to work, so let’s wreck his plans!

But you’re here because you want to spot Japanese knotweed which, weirdly, is a plant that is like my kids – it can wreck your plans. But there the similarity ends because, although I love my kids, I’m betting you’re no fan of the dreaded JK.

Through your patio

Japanese knotweed is a perennial plant – it grows new stems and leaves every year starting in the spring, matures and flowers over the summer and, as we pass into autumn, the leaves turn yellow and brown and drop, and the stems darken and dry out.

The whole purpose of this activity is to get food into the bit of the plant we can’t see, the rhizome. The knotweed rhizome is actually stem growth but below the ground, from which new buds and shoots appear, turning into new stems, while small roots form along the undersides of the rhizome and seek out water. The rhizome is the part of the plant that we, as specialists, worry about most because tiny fragments of it are perfectly capable of creating brand new knotweed plants wherever they land.

It’s from these rhizomes that Japanese knotweed is able to produce new knotweed shoots each year, using the nutrients that it has created and stored in the previous growth season. Happy, healthy knotweed is capable of producing many shoots that will go on to grow rapidly into stems that may reach heights three metres or more by mid-summer.

But what of Japanese knotweed early growth? How do you tell it apart from other sprouting flora? There’s no substitute for experience when it comes to Japanese knotweed identification but, with a little homework, even if you’ve never seen a new knotweed shoot in your life, you’ll be able to identify it in most cases.

How to Spot Japanese Knotweed Early Growth

How to identify Japanese knotweed

In early spring, Japanese knotweed shoots can look like asparagus spears with reddish/purple speckling. As the shoots grow, and healthy knotweed grows very quickly, spade-shaped leaves begin to unfurl from the stems, often beginning their life with red-tinted veins, turning lime-green like the rest of the leaf as growth continues. The new shoots can be a few millimetres to a couple of centimetres across, depending on the strength of the plant and how well-established it is.

It’s worth noting that other plants in the early stages of growth can appear similar to young Japanese knotweed. For this reason, it’s not worth panicking and getting out that old bottle of herbicide that’s been lying around in the shed for three years. If the plant in question is Japanese knotweed, treating the new stems with a herbicide will have little or no effect on the plant as a whole. The most likely outcome is that the visible stems will be damaged, but that ‘normal service will be resumed’ a couple of weeks later. If the plant you attack isn’t Japanese knotweed, you’ll probably have killed something that’s not only completely innocuous but possibly a beautiful addition to your borders.

For treatment that has lasting results, it’s always best to bring in an experienced professional contractor. There will be a cost to the service, but the long-term benefits of getting the job done properly will be worth it. When you employ PBA Solutions for Japanese knotweed treatment you get experience, knowledge and professionalism as standard, all of which adds up to a value-for-money service.

Take a look at our library of images which will help you to recognise Japanese knotweed early growth. You can check out some photos of early Japanese knotweed growth on the internet but please do so with a careful eye. Often plants are mistaken for Japanese Knotweed and you can read more on that here.

JK Next to foundations

If you think you have found Japanese knotweed…

  • Don’t panic!
  • Don’t cut the plant down.
  • Don’t pull the stems out.
  • Don’t spray the stems with any chemicals.
  • Do protect the plant from possible damage.
  • Do take photos of the plant and the area it’s growing in.
  • Do call or email a specialist invasive weeds contractor and get advice.

Need expert advice?

For a chat, expert advice and options call PBA Solutions on 0203 174 2187 or 01202 816134

Email us on and include photos of the plant in question.




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