Pocket Botanist
Check these first
- Inspect the undersides of the leaves for tiny insects.
- Look for white fuzzy growth on the bottom of the leaves.
- Check if the soil is staying too wet for too long.
Likely causes
Downy mildew
Most likelyHow to tell: You will see yellow angular spots on the upper leaf surface and white fuzzy growth on the underside. It spreads quickly in humid conditions.
What to do: Remove and destroy all infected leaves immediately to stop the spread. Improve air circulation around your plants by spacing them further apart and watering only at the base.
Aphids
Most likelyHow to tell: These tiny insects cluster on the undersides of leaves and cause yellow or brown stippling spots. You might also notice sticky honeydew on the foliage.
What to do: Spray the leaves with a strong stream of water to knock them off. If they persist, apply insecticidal soap directly to the affected areas every 5 to 7 days.
Find out what's wrong with your lettuce
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
When to worry
If the spots are spreading rapidly across the entire head, the plant may be too far gone to save. It is normal for older outer leaves to show minor wear as they age.
Stopping it coming back
Ensure your lettuce has plenty of space for airflow and avoid overhead watering to keep leaves dry.
Keep your lettuce healthy from here
Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked. Identification and a health check are free.
Questions people ask
- Can I eat lettuce with spots?
- If the spots are from aphids, you can wash them off and eat the leaves. If the spots are from downy mildew, it is best to discard the leaves as they will taste bitter and decay quickly.
- Do I need to throw away the whole plant?
- Not necessarily. If you catch the issue early and remove the affected leaves, the rest of the plant can often recover.
More problems with Lettuce
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.