Plant problems · Diseases · Vegetative growth · Act this week
Septoria leaf spot
What you see
- Round yellow spots on lower leaves that turn brown with a yellow halo
- Small dark dots in the middle of the spots
- Spots climb the plant from the bottom up
Why it happens
A fungus spread by water splashing from soil onto leaves, favoured by warm, wet conditions.
What to do
- Remove spotted leaves
- Water at the base, not on the leaves
- In veg, a copper or Bacillus subtilis product slows it
Next time
- Keep lower leaves off the soil
- Water the medium, not the leaves
Easy to confuse with
- Phosphorus deficiency: Dark, dull or bluish green leaves with brown to purple patches, often on older leaves
- Potassium deficiency: Leaf edges and tips turn yellow, then brown and crispy, starting on older leaves
- Calcium deficiency: Small brown spots with sharp edges on new and middle leaves
Not sure?
Take a photo of a lower leaf with spots, close up and ask the Grow Doctor, or send it to the grow companion on Telegram.