Pocket Botanist
Check these first
- Inspect the undersides of the leaves for pests.
- Check if the spots look like white dust or dark lesions.
- Ensure the plant has enough space for air to circulate.
Likely causes
Powdery Mildew
Most likelyHow to tell: A white, dusty fungal growth appears on the surface of the leaves. It thrives in humid conditions with poor airflow.
What to do: Remove the most affected leaves to stop the spread. Apply a neem oil spray or a mixture of water and baking soda to the remaining foliage.
Fungal Leaf Spot
PossibleHow to tell: Dark brown or black spots appear on the leaves, often with a yellow halo. These spots grow larger over time.
What to do: Avoid overhead watering to keep the leaves dry. Remove any fallen debris from the base of the plant to prevent spores from splashing back up.
Find out what's wrong with your sunflower
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
If the spots cover more than half the leaf surface or start spreading to the stem, the plant may struggle to photosynthesize.
Stopping it coming back
Water only at the base of the plant and ensure your sunflowers are spaced far enough apart for good airflow.
Sunflower: spots? Check yours with a photo
Every plant is a little different. Take a photo of your sunflower 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 save leaves that have spots?
- If the spots are minor, you can leave them. If they are extensive, it is better to prune them off.
- Is powdery mildew harmful to the whole plant?
- It weakens the plant by blocking sunlight. Treating it early is key to keeping the sunflower healthy.
Guides to these causes
More problems with Sunflower
- Why is my sunflower drooping?
- What is eating my sunflower?
- Why are my sunflower leaves turning yellow?
- Why is my sunflower not producing flowers?
- Why is my sunflower growing tall and leggy?
- Why are my sunflower's leaf tips turning brown?
- Why is my sunflower dropping its leaves?
- How do I fix root rot in my sunflower?
- Why are my sunflower 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.