Japanese Knotweed Identification

If you’re concerned that you may have Japanese Knotweed on your land, you may need some assistance with Japanese Knotweed Identification – that’s what this page is all about!

Japanese Knotweed Identification is relatively easy as it’s quite a noticable plant. It also has some key features throughout the year, but late summer/early autumn is the best time to check for it because that’s when it’s at its’ most obvious:
Autumn: The plant will have reached its maximum height with some canes reaching over 2-3m, arching over at the top and with a noticeable zig-zag arrangement of large, heart-shaped leaves all the way to the end of each stem. The current years stems will be bright green with purple/red speckles all over (a little bit like rhubarb) and obvious red bands where each ‘node’ or joint appears (a bit like bamboo). The top surface of each stem will have a frothy explosion of tiny cream coloured flowers in long tassel shapes which are very attractive to insects.
Winter: All the yellowing autumn leaves will have fell off, leaving the brown, dried stems looking quite noticeable due to their height and zig-zag growth pattern.
Spring: In amongst all the dry, dead stems from the previous year, the new shoots are relatively easy to spot because they are bright red/purple as they push through the surface. They grow incredibly rapidly – if you go back a few days later, the stems will have shot up! As they get taller, the heart-shaped leaves unfurl all the way up the stem.
Summer: What was a bare patch of ground with the previous years dead stems will now be a dense thicket of bright green stems speckled with purple streaks – just like an enormous patch of rhubarb where nothing else can grow (except for a few nettles which seem to thrive anywhere?!)

Perhaps the best method of Japanese Knotweed Identification is the use of photos:

Japanese Knotweed Identification Speckled-stem-with-red-nodes

Young growth showing speckled stem and red nodes and shoots.

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Late spring/early summer flush of growth.

 

Japanese-Knotweed-Identification-Zig-zag-red-stem-shape

Zig-zag stem, alternate leaves and the beginnings of flowering.

The key thing to remember now that you’ve read the Japanese Knotweed Identification page is that we can help you if you think you’ve got it on your land.

Take a look at our Japanese Knotweed Treatment page here: Japanese Knotweed Treatment

And finally, just to set your mind at rest, here’s a photo of some we treated earlier!:

Japanese-Knotweed-Identification-Yellowing-speckled-leaves-after-treatment

Within a fortnight of being treated, the leaves are turning spotty and yellowed before falling off prematurely.

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