Photo: Matt LavinCC BY-SA 2.0via Wikimedia Commonsresized / cropped
Spiny Horsebrush Plant Care
Tetradymia spinosa Hook. & Arn.
Updated · Sources · How we source care data
Tetradymia spinosa is a species of flowering plant in the aster family known by the common name shortspine horsebrush. It is native to the western United States, especially the basins and plateaus west of the Rocky Mountains. It grows in sagebrush, woodlands, and scrub habitat, often among shadscale in alkaline areas such as playas. It is a bushy shrub with many branches coated in woolly white fibers and growing to a maximum height around a meter. The leaves are narrow, curving, and hooklike, hardening into sharp spines up to 2.5 centimeters long. The inflorescence bears one or two flower heads which are each enveloped in four to six woolly phyllaries. Each head contains up to 8 tubular yellow disc flowers up to 1 cm long. The fruit is a densely hairy achene which may be nearly 2 cm long, including its pappus of long bristles.
Every 14–21 days
Full sun
50–85°F
20–60%
At a glance
How do you care for Spiny Horsebrush?
Plant Spiny Horsebrush in full sun (USDA zones 12a) and water a young shrub every 14–21 days until it is established. It tolerates temperatures of 50–85°F (10–29°C).
Where Is the Spiny Horsebrush Native To?
What Is the Spiny Horsebrush?
Spiny Horsebrush (Tetradymia spinosa) belongs to the Asteraceae family within the Tetradymia genus. Spiny Horsebrush is native to the western United States, especially the basins and plateaus west of the Rocky Mountains. Spiny Horsebrush is also known as Spiny Tetradymia, Tetradymia spinosa.
Spiny Horsebrush displays a low, spreading shrub growth habit, reaching up to 2 ft tall with a spread of approximately 4 ft. Spiny Horsebrush produces small yellow flowers in clusters.
Leaf size: approximately 1.5 inches.
How Often Should You Water a Spiny Horsebrush?
Water a young or newly planted Spiny Horsebrush every 14–21 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 14–21 days
Until established; then in dry spells
What Light Does the Spiny Horsebrush Need?
Spiny Horsebrush thrives in full sun.
Light Requirement
Full sun
What Temperature and Humidity Does the Spiny Horsebrush Prefer?
Tetradymia spinosa tolerates temperatures of 50–85°F. Spiny Horsebrush prefers humidity levels of 20–60%.
Temperature
50–85°F
Humidity
20–60%
What Soil Mix Works Best for a Spiny Horsebrush?
Well-draining sandy soil with low fertility. Good drainage is essential for Spiny Horsebrush to prevent waterlogging, which leads to root rot and fungal issues.
Where Should You Plant a Spiny Horsebrush?
Choose a spot with full sun and well-draining sandy soil with low fertility. Avoid low spots where water collects after rain.
Spiny Horsebrush is suited to USDA Zone 12a.
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 Spiny Horsebrush?
Spiny Horsebrush can spread to about 4 ft (1.2 m) and reach about 2 ft (1 m) tall. Space plants about 4 ft (1.2 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 Spiny Horsebrush?
Prune Spiny Horsebrush 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 Spiny Horsebrush in Winter?
Spiny Horsebrush is frost-tender (hardy to USDA zone 12). 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 Spiny Horsebrush?
Spiny Horsebrush can be propagated through seeds. Similar propagation techniques also apply to cottonbush plant care, which shares the same genus.
Is the Spiny Horsebrush Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Spiny Horsebrush, 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 Spiny Horsebrush?
Spiny Horsebrush is susceptible to aphids, 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 Spiny Horsebrush Need?
Spiny Horsebrush grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Spiny Horsebrush is native to the western United States, especially the basins and plateaus west of the Rocky Mountains. In cooler regions, grow Spiny Horsebrush as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 12a
Keep exploring plants
Spiny Horsebrush 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 Tetradymia genus — compare its care with other Tetradymia species on PlantoScan.
Tetradymia is part of the Asteraceae plant family — browse all Asteraceae genera and species.
Spiny Horsebrush thrives in bright light and direct sun — see other bright-light plants.
More Tetradymia Species
Other Tetradymia species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Tetradymia spinosa Hook. & Arn., family Asteraceae (first published in Bot. Beechey Voy. : 360 (1839)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Spiny Horsebrush, 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: Matt Lavin, CC BY-SA 2.0, Wikimedia Commons — original.
- 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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