Should I cut off the yellow leaves?

Yes, you can snip them off with clean scissors. This keeps the plant looking tidy and helps it focus energy on new growth.

Can too much sun cause yellowing?

Yes, if the leaves look bleached or washed out, the plant might be getting too much direct afternoon sun. Move it to a spot with bright, indirect light.

Knotweed: yellow leaves, causes and fixes

Check these first

Feel the soil an inch deep to see if it is soggy.
Inspect the drainage holes to ensure they are not blocked.
Check the underside of the leaves for any signs of pests.

Likely causes

Overwatering
Most likely
How to tell: The lower leaves turn yellow and feel soft or mushy to the touch. The soil surface may stay damp for more than a week.
What to do: Let the top inch of soil dry out before watering again. Ensure your pot has drainage holes so excess water can escape freely.
Nutrient Deficiency
Possible
How to tell: Older leaves turn pale yellow while the veins remain green. This often happens if the plant has been in the same pot for a long time.
What to do: Apply a balanced liquid fertilizer diluted to half strength every 4 to 6 weeks during the growing season. If the plant is severely root bound, repot it into fresh soil.

Yellow leaves on other plants

Find out what's wrong with your 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.

When to worry

Be concerned if the yellowing spreads rapidly across the whole plant. It is normal for the oldest bottom leaves to yellow and fall off occasionally as the plant grows.

Stopping it coming back

Maintain a consistent watering schedule and use a well draining potting mix to keep roots healthy.

Knotweed: yellow leaves? Check yours with a photo

Every plant is a little different. Take a photo of your 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.

Get the app · Or check it from a photo now, free

Questions people ask

Should I cut off the yellow leaves?: Yes, you can snip them off with clean scissors. This keeps the plant looking tidy and helps it focus energy on new growth.
Can too much sun cause yellowing?: Yes, if the leaves look bleached or washed out, the plant might be getting too much direct afternoon sun. Move it to a spot with bright, indirect light.

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