Photo: Cheng-Te HsuCC BY 4.0via iNaturalistresized / cropped
Collinsonia macrobracteata var. glabra Plant Care
Collinsonia macrobracteata (Masam.) Harley
Updated · Sources · How we source care data
This plant is known for its large, heart-shaped leaves that are a striking shade of deep green. Native to the southeastern United States, Collinsonia macrobracteata is highly sought after by plant collectors for its unique foliage and attractive growth habit. Its bold appearance adds a touch of drama to any garden or indoor plant collection.
Every 5–7 days
Partial shade to full sun
50–80°F
40–70%
At a glance
How do you care for Collinsonia macrobracteata var. glabra?
Water Collinsonia macrobracteata var. glabra every 5–7 days, letting the top layer of soil dry out between waterings, and give it partial shade to full sun. 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 Collinsonia macrobracteata var. glabra?
Collinsonia macrobracteata var. glabra (Collinsonia macrobracteata) belongs to the Lamiaceae family within the Collinsonia genus. Collinsonia macrobracteata var. glabra is native to United States. Collinsonia macrobracteata var. glabra is also known as Smoothleaf Horsebalm.
Collinsonia macrobracteata var. glabra displays an upright, spreading perennial growth habit, reaching up to 2.5 ft tall with a spread of approximately 1.5 ft. Collinsonia macrobracteata var. glabra produces small tubular flowers in shades of white, pink, or purple.
Leaf size: approximately 4 inches.
How Often Should You Water a Collinsonia macrobracteata var. glabra?
Collinsonia macrobracteata requires watering every 5–7 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 5–7 days
Let soil partially dry between waterings
What Light Does the Collinsonia macrobracteata var. glabra Need?
Collinsonia macrobracteata var. glabra thrives in partial shade to full sun.
Light Requirement
Partial shade to full sun
What Temperature and Humidity Does the Collinsonia macrobracteata var. glabra Prefer?
Collinsonia macrobracteata grows best at temperatures of 50–80°F. Collinsonia macrobracteata var. glabra prefers humidity levels of 40–70%.
Temperature
50–80°F
Humidity
40–70%
What Soil Mix Works Best for a Collinsonia macrobracteata var. glabra?
Well-draining loamy soil with added organic matter for moisture retention. Good drainage is essential for Collinsonia macrobracteata var. glabra to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Collinsonia macrobracteata var. glabra?
Feed Collinsonia macrobracteata var. glabra 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 Collinsonia macrobracteata var. glabra?
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 Collinsonia macrobracteata var. glabra?
Collinsonia macrobracteata var. glabra can be propagated through seeds, division of clumps, stem cuttings. Similar propagation techniques also apply to richweed plant care, which shares the same genus.
Is the Collinsonia macrobracteata var. glabra Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Collinsonia macrobracteata var. glabra, 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 Collinsonia macrobracteata var. glabra?
Collinsonia macrobracteata var. glabra is susceptible to aphids, spider mites, whiteflies. 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 Collinsonia macrobracteata var. glabra Need?
Collinsonia macrobracteata var. glabra grows outdoors in USDA Zone 8a – 9b. It survives winters down to planting zone 8a. Collinsonia macrobracteata var. glabra is native to United States.
Hardiness Zone
Zone 8a – 9b
Keep exploring plants
Collinsonia macrobracteata var. glabra 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 Collinsonia genus — compare its care with other Collinsonia species on PlantoScan.
Collinsonia is part of the Lamiaceae plant family — browse all Lamiaceae genera and species.
Collinsonia macrobracteata var. glabra thrives in bright light and direct sun — see other bright-light plants.
More Collinsonia Species
Other Collinsonia species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Collinsonia macrobracteata (Masam.) Harley, family Lamiaceae (first published in Kew Bull. 58: 486 (2003)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Collinsonia macrobracteata var. glabra, 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: Cheng-Te Hsu, CC BY 4.0, iNaturalist — original.
- Hardiness zone: USDA Zone 8a – 9b, 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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