Pocket Botanist
Check these first
- Inspect the leaves for white powdery patches.
- Look for gray fuzzy mold on the flowers.
- Check if the plant is crowded by other plants.
Likely causes
Powdery Mildew
Most likelyHow to tell: You see white, dusty spots appearing on the surface of the leaves.
What to do: Improve air circulation around the plant by moving it to a more open spot. You can wipe the leaves with a damp cloth or use a mild neem oil spray to clear the fungus.
Botrytis Blight
PossibleHow to tell: Gray, fuzzy mold appears on the flowers and stems, especially in cool and damp weather.
What to do: Remove all affected flowers and leaves immediately to stop the spread. Keep the foliage dry when watering and move the plant to a spot with better airflow.
Find out what's wrong with your begonia
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
Small spots are manageable, but if the mold covers the entire stem or flower head, it can quickly kill the plant.
Stopping it coming back
Water at the base of the plant to keep the leaves dry and ensure there is plenty of space between your plants for air to move.
Begonia: spots? Check yours with a photo
Every plant is a little different. Take a photo of your begonia 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
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Questions people ask
- Is powdery mildew harmful to my other plants?
- Yes, it spreads easily through the air. Isolate your Begonia until the spots are gone to protect your other plants.
- Should I cut off the spotted leaves?
- Yes, removing heavily spotted leaves helps the plant focus energy on healthy growth and prevents the fungus from spreading further.
Guides to these causes
More problems with Begonia
- Why is my Tuberous Begonia drooping and wilting?
- Why are my tuberous begonia's leaves turning yellow?
- Why is my tuberous begonia drooping?
- Why is my tuberous begonia growing so leggy?
- Why are there white cottony things on my Tuberous Begonia?
- Why are my Tuberous Begonia leaf tips turning brown?
- Why is my Tuberous Begonia dropping its leaves?
- Why is my Tuberous Begonia not producing flowers?
- Why are my Tuberous Begonia leaves curling?
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.