Hooker's St. Johnswort
Hypericum hookerianum · Hypericaceae
📷 H. Zell · CC BY-SA 3.0
⚠️ Millepertuis : peut induire phototoxicité. Contact de la sève avec peau exposée au soleil = réactions dermatologiques.
The gardener's calendar
Hooker's st. johnswort is in full bloom: enjoy it, watch watering in hot weather and let spent flowers feed pollinators before pruning.
ID card
- Common name
- Hooker's St. John's Wort
- Family
- Hypericaceae
- Type
- Deciduous to semi-evergreen shrub
- Adult height
- 1.5 to 2 m
- Flowering
- July to September, golden yellow flowers
- Exposure
- Full sun
- Hardiness
- Hardy to around -15 °C
- Origin
- Himalaya (India, Nepal)
✓ Taxonomy verifiedSource: AI estimate · hardiness: reliability medium.
Expert tips
The key tip
Prune just after flowering (September) to maintain shape and stimulate compact branching; this species tends to thicken and sag without intervention. Water moderately in summer but avoid excessive watering in winter.
The common mistake
Failing to prune and letting it become an unruly, woody, aging mess that flowers sparsely; sacrificing structure for misguided generosity.
The pro's trick
Every 3-4 years, give it a hard rejuvenation prune (a third of the height) in spring to regenerate old branches and trigger abundant flowering.
Seasonal watch
Very hot summers: watch for spider mites on the foliage and water at the base if the plant starts to look dull.
Care
Exposure
Install Hooker's St. John's Wort in full sun to optimize abundant and prolonged flowering. It tolerates light partial shade, but flower production will be reduced. Avoid overly hot and drying exposures in very hot Mediterranean regions.
Watering
Water regularly at planting and during the first year to encourage root establishment. Once established, the shrub tolerates moderate dry periods well thanks to its deep roots. In dry summers, weekly watering maintains optimal flowering.
Pruning and shaping
Prune lightly after flowering (September-October) to maintain a compact, bushy shape. Remove dead or damaged branches at the end of winter. More severe spring pruning stimulates branching and rejuvenates the shrub.
Soil
Hooker's St. John's Wort appreciates well-drained, neutral to slightly acidic soil. Enrich the soil at planting with compost or potting mix. Avoid overly wet or chalky soils, which can cause drainage problems.
Fertilizing
Apply balanced fertilizer in spring when growth resumes. Moderate feeding is sufficient; excess nitrogen promotes foliage at the expense of flowering. Annual mulching retains moisture and gradually enriches the soil.
Diseases and pests
The shrub is generally robust and little susceptible to disease. In overly humid conditions, watch for root rot. Aerate the center of the plant and improve drainage if stagnant moisture becomes a problem.
Did you know?
St. John's Wort owes its French name to the ancient belief that its small perforated leaves (which are actually translucent glands) resembled a thousand tiny holes; Hypericum hookerianum was named in honor of English botanist William Jackson Hooker. Its bright yellow flowers and ornamental red then bronze fruits have made it popular with modern landscapers who appreciate it for its generous summer flowering.
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
- Rose of sharonHypericum calycinum
- Tall tutsanHypericum inodorum
- Egyptian Saint John's WortHypericum aegypticum
- Kalm's St. John's-wortHypericum kalmianum
- Moser's St. John's wortHypericum moserianum
- Hypericum dummeriHypericum dummeri
Tips generated and checked by Viridia — adapt them to your local climate.