Rose of sharon
Hypericum calycinum · Hypericaceae
📷 Franz Xaver · CC BY-SA 3.0
⚠️ Contact dermique prolongé avec feuillage peut provoquer dermatite photosensibilisante chez l'humain.
The gardener's calendar
Rose of sharon is in full bloom: enjoy it, watch watering in hot weather and let spent flowers feed pollinators before pruning.
ID card
- Scientific name
- Hypericum calycinum
- Family
- Hypericaceae
- Type
- Deciduous to semi-evergreen shrub
- Adult height
- 0.60 to 0.80 m
- Flowering
- June to September, bright yellow flowers
- Foliage
- Light green, deciduous in cold climates
- Hardiness
- Down to −15 °C
- Origin
- Bulgaria, Turkey, Caucasus
✓ Taxonomy verifiedSource: AI estimate · hardiness: reliability high.
Expert tips
The key tip
Hypericum calycinum is virtually indestructible once established, but the first few years require regular watering.
The common mistake
Not pruning at all and letting it get leggy: it becomes soft, produces fewer flowers, and sprawls untidily into neighboring space.
The pro's trick
Cut back to 30 cm in February with little risk—it'll bounce back in great shape by May.
Seasonal watch
Watch the foliage during humid periods.
Care
Light exposure
Plant in full sun for generous and abundant flowering. St. John's wort appreciates at least 6 hours of direct sunlight per day. A partially shaded location is tolerated in very hot regions, but slightly reduces flower density.
Watering
Water moderately after planting to establish good root development. Once established, this shrub tolerates drought well and requires little water under normal conditions. Water during prolonged dry periods, particularly in summer, favoring deep and spaced-out watering.
Soil and planting
St. John's wort adapts to most soils, even poor or rocky ones. Well-drained soil is preferable to avoid root asphyxia. Enrich lightly with compost at planting, but avoid excess organic matter.
Pruning and maintenance
Prune lightly in late winter (February-March) to maintain a compact shape and stimulate denser flowering. Remove dead or frost-damaged stems. More drastic cutting back every 3-4 years rejuvenates the plant and promotes better branching.
Fertilizer
No fertilizer is needed in properly prepared soil. In case of very depleted soil, a light application of balanced fertilizer in spring can support growth, but remain moderate to avoid favoring foliage at the expense of flowering.
Diseases and pests
St. John's wort is very robust and seldom affected by diseases. Occasionally watch for aphids or spider mites in dry climates. Good aeration and watering at the base limit fungal problems. In very humid areas, check for the absence of root rot.
Did you know?
The Hypericum genus is rich in folklore: St. John's wort was once associated with protection against evil spells and witchcraft in medieval Europe. Its French name "mille-pertuis" refers to the small translucent dots visible on its leaves in sunlight, which resemble tiny perforations. Today, certain Hypericum species are still studied for their natural properties, though consumption should always remain under medical advice.
Where to buy it
Best planted in autumn so the roots settle in before summer, or in early spring once the frost has passed. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, October, November.
Add this plant to my garden →Plants from the same family
- Tall tutsanHypericum inodorum
- Egyptian Saint John's WortHypericum aegypticum
- Hooker's St. JohnswortHypericum hookerianum
- Hypericum dummeriHypericum dummeri
- 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.