American Horse-gentian Plant Care
Triosteum aurantiacum var. illinoense (Wiegand) E.J.Palmer & Steyerm.
Updated · Sources · How we source care data
This plant is easily recognized by its large, oval-shaped leaves with a vibrant orange hue. Originating from the woodlands of Illinois, this variety is highly sought after by plant collectors for its striking foliage and unique coloration that adds a pop of brightness to any garden.
Every 7–10 days
Partial to full shade
50–80°F
40–70%
At a glance
How do you care for American Horse-gentian?
Water American Horse-gentian every 7–10 days, letting the top layer of soil dry out between waterings, and give it partial to full shade. It prefers temperatures of 50–80°F (10–27°C) and 40–70% humidity. Fertilize it every 6 months during the growing season.
What Is the American Horse-gentian?
American Horse-gentian (Triosteum aurantiacum var. illinoense) belongs to the Caprifoliaceae family within the Triosteum genus. American Horse-gentian is native to United States, Canada. American Horse-gentian is also known as Tinker's Weed, Feverwort.
American Horse-gentian displays a clump-forming perennial growth habit, reaching up to 2 ft tall with a spread of approximately 2 ft. American Horse-gentian produces small, tubular flowers in clusters.
Leaf size: approximately 6 inches.
How Often Should You Water a American Horse-gentian?
Triosteum aurantiacum var. illinoense 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 American Horse-gentian Need?
American Horse-gentian thrives in partial to full shade. The optimal light range is 100–500 lux. Avoid placing American Horse-gentian in direct, harsh sunlight for extended periods, as this can scorch the foliage.
Light Requirement
Partial to full shade
100–500 lux
What Temperature and Humidity Does the American Horse-gentian Prefer?
Triosteum aurantiacum var. illinoense grows best at temperatures of 50–80°F. American Horse-gentian prefers humidity levels of 40–70%.
Temperature
50–80°F
Humidity
40–70%
What Soil Mix Works Best for a American Horse-gentian?
Moist, well-draining soil rich in organic matter. Good drainage is essential for American Horse-gentian to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a American Horse-gentian?
Feed American Horse-gentian 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 American Horse-gentian?
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 American Horse-gentian?
American Horse-gentian can be propagated through seeds, division of rhizomes. Similar propagation techniques also apply to horse-true plant care, which shares the same genus.
Is the American Horse-gentian Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list American Horse-gentian, 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 American Horse-gentian?
American Horse-gentian is susceptible to aphids, spider mites, scale insects. 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 American Horse-gentian Need?
American Horse-gentian grows outdoors in USDA Zone 4a – 8b. It survives winters down to planting zone 4a. American Horse-gentian is native to United States, Canada.
Hardiness Zone
Zone 4a – 8b
Keep exploring plants
American Horse-gentian 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 Triosteum genus — compare its care with other Triosteum species on PlantoScan.
Triosteum is part of the Caprifoliaceae plant family — browse all Caprifoliaceae genera and species.
American Horse-gentian 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: Triosteum aurantiacum var. illinoense (Wiegand) E.J.Palmer & Steyerm., family Caprifoliaceae (first published in Ann. Missouri Bot. Gard. 22: 651 (1935)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list American Horse-gentian, 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 4a – 8b, 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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