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Japanese knotweed · Reynoutria japonica

Why are the tips of my Japanese knotweed leaves turning brown?

Brown tips on Japanese knotweed are typically a sign of environmental stress, often related to extreme heat or lack of water. Check the soil moisture first to see if the plant is thirsty.

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Check these first

  1. Feel the soil to see if it is bone dry.
  2. Observe if the browning happens after a very hot day.
  3. Check if the plant is getting too much direct afternoon sun.

Likely causes

  1. Drought Stress

    Most likely

    How to tell: The leaf tips become crispy and brown while the rest of the leaf looks dull. This happens during long, hot, dry spells.

    What to do: Water the plant deeply once every 7 to 14 days. Ensure the water reaches the root zone rather than just wetting the surface.

  2. Sun Scorch

    Possible

    How to tell: The tips and edges of the leaves turn brown after a sudden heatwave or exposure to intense afternoon sun. The plant may look wilted during the hottest part of the day.

    What to do: Provide some afternoon shade if possible. If the plant is in a container, move it to a spot with bright indirect light.

Brown tips on other plants

Find out what's wrong with your japanese knotweed

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

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When to worry

It is normal for the plant to show some browning during the peak of summer heat. Worry if the browning spreads to the stems or causes the whole leaf to curl.

Stopping it coming back

Mulch around the base of the plant to help the soil retain moisture during hot weather.

Japanese knotweed: brown tips? Check yours with a photo

Every plant is a little different. Take a photo of your japanese knotweed and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

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Questions people ask

Can I trim the brown tips off?
You can snip the brown parts off with clean scissors for aesthetic reasons. Just be careful not to cut into the healthy green tissue.
Does this mean I should water every day?
No, do not water every day. Even in heat, this plant prefers a deeper soak every 7 to 14 days rather than frequent light watering.

Guides to these causes

More problems with Japanese knotweed

Back to the Japanese knotweed guide

This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.