Japanese Swertia Plant Care
Swertia japonica Makino
Updated · Sources · How we source care data
Swertia japonica, also known as senburi (センブリ), is a biennial plant species in the family Gentianaceae. It is one of the most widely-used medicinal herbs in Japan.
Every 7–10 days
Partial shade to full shade
50–75°F
40–70%
At a glance
How do you care for Japanese Swertia?
Water Japanese Swertia every 7–10 days, letting the top layer of soil dry out between waterings, and give it partial shade to full shade. It prefers temperatures of 50–75°F (10–24°C) and 40–70% humidity. Fertilize it every 6 months during the growing season.
What Is the Japanese Swertia?
Japanese Swertia (Swertia japonica) belongs to the Gentianaceae family within the Swertia genus. Japanese Swertia is also known as Japanese Felwort.
Japanese Swertia displays an upright, clumping perennial growth habit, reaching up to 1.5 ft tall with a spread of approximately 1 ft. Japanese Swertia produces small, star-shaped flowers in shades of blue, purple, or white.
Leaf size: approximately 3 inches.
How Often Should You Water a Japanese Swertia?
Swertia japonica requires watering every 7–10 days. Allow the top layer of soil to dry between waterings to prevent root rot. Reduce watering frequency during winter when growth slows.
Watering Frequency
Every 7–10 days
Let soil partially dry between waterings
What Light Does the Japanese Swertia Need?
Japanese Swertia thrives in partial shade to full shade. The optimal light range is 100–500 lux. Avoid placing Japanese Swertia in direct, harsh sunlight for extended periods, as this can scorch the foliage.
Light Requirement
Partial shade to full shade
100–500 lux
What Temperature and Humidity Does the Japanese Swertia Prefer?
Swertia japonica grows best at temperatures of 50–75°F. Japanese Swertia prefers humidity levels of 40–70%.
Temperature
50–75°F
Humidity
40–70%
What Soil Mix Works Best for a Japanese Swertia?
Well-draining, loamy soil with added organic matter for moisture retention. Good drainage is essential for Japanese Swertia to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Japanese Swertia?
Feed Japanese Swertia every 6 months during the growing season (spring and summer) with a balanced fertilizer diluted to the strength on the label.
Pause feeding in autumn and winter, when growth slows, and never fertilize dry soil — water first.
Fertilizing
Every 6 months
During the growing season
The PlantoScan app can remind you when to water and when to fertilize each plant.
How Do You Repot a Japanese Swertia?
Repot every 2-3 years in early spring. Choose a pot one size larger than the current container, and ensure it has drainage holes to allow excess water to escape.
How Do You Propagate a Japanese Swertia?
Japanese Swertia can be propagated through seeds, division of root ball. Similar propagation techniques also apply to swertia bimaculata plant care, which shares the same genus.
Is the Japanese Swertia Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Japanese Swertia, 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 Japanese Swertia?
Japanese Swertia is susceptible to aphids, slugs, snails. 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 Japanese Swertia Need?
Japanese Swertia grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. In cooler regions, grow Japanese Swertia as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 12a
Keep exploring plants
Japanese Swertia 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 Swertia genus — compare its care with other Swertia species on PlantoScan.
Swertia is part of the Gentianaceae plant family — browse all Gentianaceae genera and species.
Japanese Swertia copes with lower light than most plants — browse the full list of low-light plants.
Related Plant Care Guides
Closely related plants with similar care requirements:
Sources
- Scientific name & taxonomy: Swertia japonica Makino, family Gentianaceae (first published in Bot. Mag. (Tokyo) 24: 294 (1910)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Japanese Swertia, 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.
- Hardiness zone: USDA Zone 12a, calculated from the plant's minimum temperature.
- 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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