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Japanese knotweed in September


Japanese knotweed isn’t always the easiest plant to identify, and there are lots of other weeds it can be mistaken for. To confuse things further, Japanese knotweed will look different depending on the season.

The best time of year to identify Japanese knotweed is during the late summer/autumn months, particularly in September. The later summer months are also the best time to treat it, so all the more reason identify it as soon as possible.

Read more: When Is the Best Time to Treat Japanese Knotweed?

To help you check if you have Japanese knotweed growing on or near your property, we’ve compiled the following guidance on how to spot Japanese knotweed in September.


What does Japanese knotweed look like in September?


Japanese knotweed in autumn


Japanese knotweed in September will have started to flower. Look out for clusters of tiny off-white flowers up to 10cm in length. You should also expect to see lots of green, heart-shaped leaves. As a result, Japanese knotweed during the autumn months will likely be dense and bushy in appearance.

It is important to note that as we get into late September/early October time the leaves will begin to wilt and turn a yellow/orange colour. They will also start looking smaller and more brittle.

Japanese knotweed stems can grow up to 3 metres tall, and they will likely still be around 2-3 metres tall in September. What will change about the stems, though, is that their red/purple colour will begin to turn brown.

Then, moving into the later autumn months and winter, the leaves will begin to fall.


In September, Japanese knotweed has...

  • A very bushy appearance
  • Elongated bunches of tiny cream flowers
  • Green heart-shaped leaves at the beginning of September
  • Yellow/orange leaves towards the end of the month
  • 2-3 metres tall
  • Brown stems
  • Leaves that fall at the end of September


What should I do if I suspect Japanese knotweed?

Concerned that Japanese knotweed may be growing on or near your property? We can help! Get in touch with the Taylor Total Weed Control team as soon as possible and we can perform a free, discreet, no-obligation survey of your suspect shrub.

We offer a range of treatment plans, including excavation and removal, herbicide treatment and excavation and burial.

If you’re still not sure if you’re dealing with Japanese knotweed, send us a photo and our Japanese knotweed experts will get back to you with a definitive verdict.


Identify Japanese knotweed with a photo

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