Troubleshooting
Hairy St John's-wort problems — and how to fix them
Hairy St John's-wort (Hypericum hirsutum) is generally low-drama, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Fungal leaf spot
Dark brown spots appear on leaves in humid conditions with poor air circulation; remove affected leaves and avoid overhead watering.
Aphid infestations
Colonies of greenfly can build up on young shoot tips in spring; blast off with water or apply insecticidal soap — avoid systemic insecticides near flowering plants where pollinators are active.
Prevent hairy st john's-wort problems before they start
Most hairy st john's-wort issues are care-mismatch, not bad luck. Dial in the basics:
Hairy St John's-wort problems — FAQ
Why is my hairy st john's-wort fungal leaf spot?
Dark brown spots appear on leaves in humid conditions with poor air circulation; remove affected leaves and avoid overhead watering.
Why is my hairy st john's-wort aphid infestations?
Colonies of greenfly can build up on young shoot tips in spring; blast off with water or apply insecticidal soap — avoid systemic insecticides near flowering plants where pollinators are active.