How to Identify Japanese Knotweed (Reynoutria japonica) Through the Year

This video will show you how to identify Japanese Knotweed (Reynoutria japonica) at any time of year, spring, summer, autumn, and winter.

Japanese knotweed is one of the most aggressive and invasive non-native plants in the UK and many other countries.

Japanese knotweed decreases property value, outcompetes native and garden plants, and it is extremely hard to remove once established.
This guide helps homebuyers, gardeners, and surveyors identify Japanese knotweed year-round. Because Japanese knotweed changes SO much through the year!

In this video, you’ll learn:

Spring identification: red-purple shoots and rolled leaves
Summer identification: tall, bamboo-like stems and spade-shaped green leaves
Autumn identification: creamy-white flower clusters
Winter identification: dry, hollow brown canes and rhizomes below the ground.

At 2:04, I also show you an example of herbicide-treated Japanese knotweed (with glyphosate).

You'll learn how to spot the difference between Japanese knotweed and other lookalike plants such as giant knotweed, bindweed, and bamboo.

I’ll also give you guidance on the next steps you need to take for treatment, and where you can find the legal information you need to know about Japanese knotweed removal in the UK.

The quicker you can identify Japanese knotweed, the easier your Japanese knotweed will be to eradicate.

Note: Japanese knotweed is known by a number of different latin names, including:
Reynoutria japonica
Fallopia japonica
Polygonum cuspidatum

⌚ Timestamps
00:00 – Why Japanese knotweed is hard to identify
00:41 – Spring: Identifying young red shoots and stems
02:19 – Summer: Bamboo-like canes and spade-shaped leaves
04:18 – Late Summer & Autumn: Creamy-white flowers
05:16 – Winter: Brittle brown canes and rhizomes
07:04 – Giant knotweed vs Japanese knotweed
07:39 – Other lookalikes: Bamboo, dock, and bindweed
08:56 – Treatment & UK legal info about Japanese knotweed

Please note: Thoughts shared in this video are my personal opinions. I'm not paid any money to promote the gardening products I talk about or use in this video.

Happy gardening! 🌸