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Check these first
- Test your water for nitrate and phosphate levels.
- Check if the plant is receiving enough natural light.
- Inspect the stems for signs of decay.
Likely causes
Nutrient deficiency
Most likelyHow to tell: Older leaves turn yellow while new growth remains small or pale.
What to do: Add a liquid aquatic plant fertilizer to the water. Follow the label instructions for your tank size. Repeat every 2 to 4 weeks during the growing season.
Low light levels
PossibleHow to tell: The entire plant looks pale and yellow, especially the lower sections.
What to do: Move your container to a spot with more bright, indirect light. If indoors, consider adding a full spectrum grow light for 8 to 10 hours daily.
Find out what's wrong with your eurasian watermilfoil
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.
Scan with your phone's camera to get the app
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When to worry
Worry if the yellowing spreads rapidly across the entire colony. It is normal for a few older, bottom leaves to yellow occasionally as the plant grows.
Stopping it coming back
Maintain consistent nutrient levels and ensure the plant receives bright, indirect light daily.
Eurasian watermilfoil: yellow leaves? Check yours with a photo
Every plant is a little different. Take a photo of your eurasian watermilfoil 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.
Scan with your phone's camera to get the app
Or go to pocketbotanist.app/get on your phone
Get the app · Or check it from a photo now, free
Questions people ask
- Can I use regular houseplant fertilizer?
- No, you must use a fertilizer specifically formulated for aquatic plants. Regular fertilizers can cause dangerous algal blooms and harm aquatic life.
- Does yellowing mean my water is dirty?
- Not necessarily, but it often means the water lacks the specific nutrients the plant needs. Test your water to be sure.
More problems with Eurasian watermilfoil
Back to the Eurasian watermilfoil 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.