Square-stemmed St John's-wort
Hypericum tetrapterum · Hypericaceae
The gardener's calendar
Ideal time to plant square-stemmed 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
- Flowering
- June to September, yellow flowers
- Adult size
- 0.6 to 1 m in height
- Growth
- Fast
- Hardiness
- Very hardy, down to -15°C
- Origin
- Europe, Western Asia
- Soil type
- Moist to fresh, tolerates poor soils
Care
Watering
Four-winged St. John's Wort appreciates fresh, well-draining soil. Water regularly during the growing season, especially in dry periods, to maintain substrate moisture. In winter, reduce watering but don't let the soil dry out completely.
Light exposure
Place this plant in full sun or partial shade for optimal flowering. It tolerates partially shaded areas well but will flower more abundantly with at least 4 hours of direct sunlight per day.
Pruning
Perform light spring pruning to stimulate branching and maintain a compact shape. Remove dead wood and weak stems. An autumn pruning after flowering helps prepare the plant for winter.
Soil
Four-winged St. John's Wort thrives in poor to average soils, as long as they remain moist. Clayey or loamy soil with good moisture retention is ideal. Improve sandy soils with compost before planting.
Fertilizer
This hardy plant doesn't require regular feeding. A moderate application of well-decomposed compost each spring is plenty. In very poor soil, balanced fertilizer in spring can support growth.
Diseases and pests
St. John's Wort is generally robust and rarely troubled by disease. Watch for mealybugs and aphids in hot, dry conditions. Rust can appear in humid environments; ensure good air circulation around the plant.
Did you know?
St. John's Wort has long been harvested for its properties historically attributed in phytotherapy. Its Latin name "Hypericum" means "above an icon": in the Middle Ages, these plants were hung in churches for their supposed protective power. The crushed flowers release an intense red pigment, once used as a natural dye.
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
- Kalm's St. John's-wortHypericum kalmianum
Tips generated and checked by Viridia — adapt them to your local climate.