Purpletop Plant Care
Tridens flavus Hitchc.
Updated · Sources · How we source care data
Tridens flavus, known as purpletop, purpletop tridens, tall redtop, greasy grass, and grease grass, is a large, robust perennial bunchgrass.
Every 7–14 days
Full sun to partial shade
60–85°F
40–70%
At a glance
How do you care for Purpletop?
Water Purpletop every 7–14 days, letting the top layer of soil dry out between waterings, and give it full sun to partial shade. It prefers temperatures of 60–85°F (16–29°C) and 40–70% humidity. Fertilize it every 8 months during the growing season.
What Is the Purpletop?
Purpletop (Tridens flavus) belongs to the Poaceae family within the Tridens genus. Purpletop is also known as Purpletop Grass, Talltop Tridens, Yellowtop Tridens.
Purpletop displays a tall, upright grass growth habit, reaching up to 6 ft tall with a spread of approximately 2 ft. Purpletop produces small inconspicuous flowers in terminal panicles.
Leaf size: approximately 12 inches.
How Often Should You Water a Purpletop?
Tridens flavus requires watering every 7–14 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 7–14 days
Let soil partially dry between waterings
What Light Does the Purpletop Need?
Purpletop thrives in full sun to partial shade.
Light Requirement
Full sun to partial shade
What Temperature and Humidity Does the Purpletop Prefer?
Tridens flavus grows best at temperatures of 60–85°F. Purpletop prefers humidity levels of 40–70%.
Temperature
60–85°F
Humidity
40–70%
What Soil Mix Works Best for a Purpletop?
Well-draining loamy soil with good fertility. Good drainage is essential for Purpletop to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Purpletop?
Feed Purpletop every 8 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 8 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 Purpletop?
Divide clumps 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 Purpletop?
Purpletop can be propagated through seeds, division of clumps. Similar propagation techniques also apply to eragrostis tridens plant care, which shares the same genus.
Is the Purpletop Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Purpletop, 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 Purpletop?
Purpletop is susceptible to grasshoppers, aphids, cutworms. 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 Purpletop Need?
Purpletop grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. In cooler regions, grow Purpletop as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 13a
Keep exploring plants
Purpletop 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 Tridens genus — compare its care with other Tridens species on PlantoScan.
Tridens is part of the Poaceae plant family — browse all Poaceae genera and species.
Purpletop 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: Tridens flavus Hitchc., family Poaceae (first published in Rhodora 8: 210 (1906)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Purpletop, 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 13a, 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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