Pocket Botanist
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Check these first
- Inspect the undersides of yellow leaves for fuzzy growth.
- Touch the soil to see if it feels soggy or waterlogged.
- Check if the plant is crowded by other nearby plants.
Likely causes
Downy mildew
Most likelyHow to tell: You will see yellow patches on the top of the leaves with a fuzzy gray growth underneath. This happens when the weather is damp and cool.
What to do: Remove the infected leaves immediately to stop the spread. Improve air circulation around the plant by thinning out dense growth and avoid overhead watering.
Overwatering
Most likelyHow to tell: The lower leaves turn yellow and feel soft or mushy. The soil stays wet for a long time after you water.
What to do: Let the top inch of soil dry out before watering again. Ensure your pot has drainage holes so extra water can escape.
When to worry
If the yellowing spreads rapidly across the whole plant, it is likely a fungal infection that needs quick action. A few yellow leaves at the base are normal as the plant ages.
Stopping it coming back
Water at the base of the plant to keep leaves dry and ensure there is plenty of space for air to move between stems.
Not sure which one it is? Photograph your purple deadnettle.
This page lists the usual causes. Pocket Botanist looks at your actual leaf and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.
Questions people ask
- Can I save a plant with downy mildew?
- Yes, if you catch it early. Prune away the affected parts and move the plant to a spot with better airflow.
- Does yellowing mean I need fertilizer?
- Usually not. Purple deadnettle is quite hardy and rarely needs extra food. Check your watering and light first.
More problems with Purple deadnettle
Back to the Purple deadnettle guide
This article was generated with AI from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.