Pocket BotanistCheck these first
- Look for a white, powdery substance on the leaves.
- Check if the plant is crowded by other plants.
- Feel if the foliage stays wet for long periods.
Likely causes
Powdery mildew
Most likelyHow to tell: You will see a white, flour like dusting on the leaves and stems. It usually starts on older leaves and spreads upward.
What to do: Remove the most heavily infected leaves and dispose of them in the trash. Spray the remaining foliage with a mixture of one tablespoon of baking soda in a gallon of water.
High humidity and poor airflow
PossibleHow to tell: The fungus grows rapidly when nights are cool and days are humid. Lack of wind or space around the plant prevents moisture from evaporating.
What to do: Thin out your plants to improve airflow. Always water at the base of the plant rather than overhead to keep the leaves dry.
When to worry
If the mildew covers most of the foliage, the plant will struggle to photosynthesize and may stop blooming. Treat it as soon as you see the first spot.
Stopping it coming back
Plant in full sun with plenty of space between plants to ensure good air circulation. Water only at the soil level, never over the leaves.
Not sure which one it is? Photograph your pot marigold.
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
- Is the white stuff a bug?
- No, it is a fungus. It looks like someone sprinkled flour on your plant.
- Should I throw the plant away?
- Not necessarily. If you catch it early, you can prune the bad leaves and treat the rest to save the plant.
More problems with Pot Marigold
Back to the Pot Marigold 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.