Photo: Vítor JorgeCC BY 4.0via iNaturalistresized / cropped
Large-leaved St. John's Wort Plant Care
Hypericum grandifolium Choisy
Updated · Sources · How we source care data
With its large, glossy, ovate leaves, Hypericum grandifolium originates from the mountainous regions of Central and South America. This plant's striking foliage and vibrant yellow flowers make it highly desirable to plant collectors looking to add a tropical touch to their gardens.
Every 7–10 days
Full sun to partial shade
50–80°F
40–70%
At a glance
How do you care for Large-leaved St. John's Wort?
Plant Large-leaved St. John's Wort in full sun to partial shade (USDA zones 9a–11b) and water a young shrub every 7–10 days until it is established. It tolerates temperatures of 50–80°F (10–27°C). Fertilize it every 6 months during the growing season.
What Is the Large-leaved St. John's Wort?
Large-leaved St. John's Wort (Hypericum grandifolium) belongs to the Hypericaceae family within the Hypericum genus. Large-leaved St. John's Wort is native to the Canary Islands and Madeira in Macaronesia.
Large-leaved St. John's Wort displays an upright, bushy shrub growth habit, reaching up to 3 ft tall with a spread of approximately 2 ft. Large-leaved St. John's Wort produces bright yellow, star-shaped flowers with prominent stamens.
Leaf size: approximately 4 inches.
How Often Should You Water a Large-leaved St. John's Wort?
Water a young or newly planted Large-leaved St. John's Wort every 7–10 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established shrubs mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.
Watering Frequency
Every 7–10 days
Until established; then in dry spells
What Light Does the Large-leaved St. John's Wort Need?
Large-leaved St. John's Wort thrives in full sun to partial shade.
Light Requirement
Full sun to partial shade
What Temperature and Humidity Does the Large-leaved St. John's Wort Prefer?
Hypericum grandifolium tolerates temperatures of 50–80°F. Large-leaved St. John's Wort prefers humidity levels of 40–70%.
Temperature
50–80°F
Humidity
40–70%
What Soil Mix Works Best for a Large-leaved St. John's Wort?
Well-draining loamy soil with added organic matter for moisture retention. Good drainage is essential for Large-leaved St. John's Wort to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Large-leaved St. John's Wort?
Feed Large-leaved St. John's Wort every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established shrubs in good soil often need little extra feeding, so let weak growth or pale foliage guide you.
Stop feeding by late summer so new growth can harden before winter.
Fertilizing
Every 6 months
During the growing season
The PlantoScan app can remind you when to water and when to fertilize each plant.
Where Should You Plant a Large-leaved St. John's Wort?
Choose a spot with full sun to partial shade and well-draining loamy soil with added organic matter for moisture retention. Avoid low spots where water collects after rain.
Large-leaved St. John's Wort is suited to USDA Zone 9a – 11b.
Plant container-grown or balled-and-burlapped shrubs in spring or early autumn, setting the root flare at soil level, and water well after planting.
How Far Apart Should You Plant a Large-leaved St. John's Wort?
Large-leaved St. John's Wort can spread to about 2 ft (0.6 m) and reach about 3 ft (1 m) tall. Space plants about 2 ft (0.6 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.
Planning a row or hedge? Try the plant spacing calculator.
How Do You Prune a Large-leaved St. John's Wort?
Prune Large-leaved St. John's Wort while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.
If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the shrub in one year.
How Do You Care for a Large-leaved St. John's Wort in Winter?
Large-leaved St. John's Wort is frost-tender (hardy to USDA zone 9). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.
How Do You Propagate a Large-leaved St. John's Wort?
Large-leaved St. John's Wort can be propagated through softwood cuttings, seeds. Similar propagation techniques also apply to st johns wort plant care, which shares the same genus.
Is the Large-leaved St. John's Wort Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Large-leaved St. John's Wort, so we can't confirm whether it is safe for cats and dogs. Keep pets from chewing it as a precaution.
This is a general caution, not veterinary or medical advice. If your pet ate a plant, contact your vet or animal poison control.
See all plants toxic to cats and plants toxic to dogs.
What Pests and Diseases Affect the Large-leaved St. John's Wort?
Large-leaved St. John's Wort is susceptible to aphids, scale insects, spider mites. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.
Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.
What USDA Hardiness Zone Does the Large-leaved St. John's Wort Need?
Large-leaved St. John's Wort grows outdoors in USDA Zone 9a – 11b. It survives winters down to planting zone 9a. Large-leaved St. John's Wort is native to the Canary Islands and Madeira in Macaronesia. In cooler regions, grow Large-leaved St. John's Wort as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 9a – 11b
Keep exploring plants
Large-leaved St. John's Wort is one of many species covered in the complete plant care and identification guide, which groups plants by genus, attribute, and popularity.
It belongs to the Hypericum genus — compare its care with other Hypericum species on PlantoScan.
Hypericum is part of the Hypericaceae plant family — browse all Hypericaceae genera and species.
Large-leaved St. John's Wort thrives in bright light and direct sun — see other bright-light plants.
Related Plant Care Guides
Closely related plants with similar care requirements:
Sources
- Scientific name & taxonomy: Hypericum grandifolium Choisy, family Hypericaceae (first published in Prodr. Monogr. Hypéric. : 38 (1821)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Large-leaved St. John's Wort, so we can't confirm whether it is safe for cats and dogs. Checked against the ASPCA plant list; any other toxicity note on this page comes from PlantoScan's plant database.
- Photo: Vítor Jorge, CC BY 4.0, iNaturalist — original.
- Hardiness zone: USDA Zone 9a – 11b, estimated from the plant's typical growing conditions.
- Care values(watering, light, temperature, humidity, soil, fertilizing): PlantoScan's plant database, filtered by automatic plausibility checks — values that fail them are hidden. How we source and check plant data.
Spotted a mistake? Email info@upvision.media with the page link — we check and correct reported errors.
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