Troubleshooting
St. John's Wort problems — and how to fix them
St. John's Wort (Hypericum perforatum) 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.
Invasive spreading
Spreads aggressively by rhizome and prolific seed and is a noxious weed in parts of North America and Australia; deadhead and confine, or check local regulations before planting.
Rust disease
Orange pustules (Melampsora) disfigure foliage in damp, crowded conditions; improve spacing, remove infected leaves and avoid overhead watering.
Root rot in wet soil
Waterlogged or heavy soils cause crown and root rot; plant in sharply drained ground and avoid overwatering.
Livestock and pet photosensitivity
Hypericin causes sun-triggered skin damage in animals that graze it; site away from pasture and pet runs.
Prevent st. john's wort problems before they start
Most st. john's wort issues are care-mismatch, not bad luck. Dial in the basics:
Looking for st. john's wort in general rather than its problems? Read the full st. john's wort care guide — light, water, soil and feeding.
St. John's Wort problems — FAQ
Why is my st. john's wort invasive spreading?
Spreads aggressively by rhizome and prolific seed and is a noxious weed in parts of North America and Australia; deadhead and confine, or check local regulations before planting.
Why is my st. john's wort rust disease?
Orange pustules (Melampsora) disfigure foliage in damp, crowded conditions; improve spacing, remove infected leaves and avoid overhead watering.
Why is my st. john's wort root rot in wet soil?
Waterlogged or heavy soils cause crown and root rot; plant in sharply drained ground and avoid overwatering.
Why is my st. john's wort livestock and pet photosensitivity?
Hypericin causes sun-triggered skin damage in animals that graze it; site away from pasture and pet runs.