Troubleshooting
Perforate St John's-wort problems — and how to fix them
Perforate St John's-wort (Hypericum perforatum) 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.
Rust (Melampsora hypericorum)
Orange-yellow pustules appear on leaf undersides in late summer; worse in damp conditions — improve air circulation and remove infected material promptly.
Self-seeding and invasiveness
Produces abundant viable seed and can colonise bare soil aggressively; deadhead after flowering if spread is not desired, particularly in naturalistic plantings.
Prevent perforate st john's-wort problems before they start
Most perforate st john's-wort issues are care-mismatch, not bad luck. Dial in the basics:
Perforate St John's-wort problems — FAQ
Why is my perforate st john's-wort rust (melampsora hypericorum)?
Orange-yellow pustules appear on leaf undersides in late summer; worse in damp conditions — improve air circulation and remove infected material promptly.
Why is my perforate st john's-wort self-seeding and invasiveness?
Produces abundant viable seed and can colonise bare soil aggressively; deadhead after flowering if spread is not desired, particularly in naturalistic plantings.