St John's wort
Hypericum perforatum · Hypericaceae
The gardener's calendar
Ideal time to plant st john's wort: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Deciduous to semi-evergreen
- Blooming
- June to September, yellow flowers
- Mature size
- 24 to 35 inches tall
- Growth
- Fast and vigorous
- Hardiness
- Very hardy (down to 5°F/-15°C)
- Origin
- Europe and Western Asia
- Soil type
- Well-drained, undemanding
Care
Light Exposure
Common St. John's wort thrives in full sun for optimal blooming. It tolerates partial shade but will flower less abundantly. Place it in a bright, airy location to encourage vigor.
Watering
Water moderately and let the soil dry out slightly between waterings. Once established, it's very drought-tolerant. Avoid excess moisture, which promotes root rot.
Soil
This plant adapts to almost any well-drained soil. It prefers poor or gravelly ground rather than rich soil. Improve drainage if your soil is clay-based or compacted.
Pruning
Cut back the plant in spring (March-April) to 6-8 inches from the ground to encourage compact branching. Remove dead or damaged stems. Light pruning after flowering extends the blooming period.
Fertilizing
St. John's wort is undemanding and requires only moderate feeding. A balanced fertilizer in spring is sufficient. Too much nitrogen promotes foliage at the expense of flowers.
Diseases and Pests
This plant is generally very healthy. Watch for aphids during very hot and dry conditions. Powdery mildew may appear if humidity is excessive and air circulation is poor.
Did you know?
Perforated St. John's wort owes its scientific name 'perforatum' to the tiny translucent dots visible on its leaves—these are oleiferous glands containing active substances that humans have used for millennia. In the Middle Ages, it was called 'Devil's Scourge' and hung above doorways to ward off evil spirits, while its benefits were already recognized in traditional herbal medicine.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
Add this plant to my garden →Plants from the same family
- Rose of sharonHypericum calycinum
- Tall tutsanHypericum inodorum
- Egyptian Saint John's WortHypericum aegypticum
- Hooker's St. JohnswortHypericum hookerianum
- Moser's St. John's wortHypericum moserianum
- Hypericum dummeriHypericum dummeri
Tips generated and checked by Viridia — adapt them to your local climate.