Troubleshooting
Goldencup St. John's Wort problems — and how to fix them
Goldencup St. John's Wort (Hypericum patulum) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Hypericum rust (Melampsora hypericorum)
Orange pustules appear on leaf undersides in humid conditions. Remove infected leaves, improve air circulation, and apply a sulphur-based fungicide if infection is severe.
Frost dieback
In zones 6 and colder, stems may die back in harsh winters. The plant typically resprouts from the base in spring. Cut back dead wood once new growth appears.
Aphid colonies
Soft new growth attracts aphids, which cause distorted shoot tips and sticky honeydew. Blast off with water, introduce ladybirds, or apply insecticidal soap. Avoid high-nitrogen feeding which promotes soft growth.
Prevent goldencup st. john's wort problems before they start
Most goldencup st. john's wort issues are care-mismatch, not bad luck. Dial in the basics:
Goldencup St. John's Wort problems — FAQ
Why is my goldencup st. john's wort hypericum rust (melampsora hypericorum)?
Orange pustules appear on leaf undersides in humid conditions. Remove infected leaves, improve air circulation, and apply a sulphur-based fungicide if infection is severe.
Why is my goldencup st. john's wort frost dieback?
In zones 6 and colder, stems may die back in harsh winters. The plant typically resprouts from the base in spring. Cut back dead wood once new growth appears.
Why is my goldencup st. john's wort aphid colonies?
Soft new growth attracts aphids, which cause distorted shoot tips and sticky honeydew. Blast off with water, introduce ladybirds, or apply insecticidal soap. Avoid high-nitrogen feeding which promotes soft growth.