Wedgeleaf Thistle Plant Care
Cirsium crassicaule Jeps.
Updated · Sources · How we source care data
Cirsium crassicaule is a species of thistle known by the common name slough thistle. It is endemic to the San Joaquin Valley of California, where it is known primarily from freshwater wetlands.
Every 7–14 days
Full sun
60–80°F
40–70%
At a glance
How do you care for Wedgeleaf Thistle?
Water Wedgeleaf Thistle every 7–14 days, letting the top layer of soil dry out between waterings, and give it full sun. It prefers temperatures of 60–80°F (16–27°C) and 40–70% humidity. Fertilize it every 6 months during the growing season.
What Is the Wedgeleaf Thistle?
Wedgeleaf Thistle (Cirsium crassicaule) belongs to the Asteraceae family within the Cirsium genus. Wedgeleaf Thistle is native to only a few locations in Kern, Kings, and San Joaquin Counties. Wedgeleaf Thistle is also known as Canyon Thistle.
Wedgeleaf Thistle displays a tall, spiky perennial growth habit, reaching up to 4 ft tall with a spread of approximately 2 ft. Wedgeleaf Thistle produces showy purple or pink thistle-like flower heads.
Leaf size: approximately 12 inches.
How Often Should You Water a Wedgeleaf Thistle?
Cirsium crassicaule 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 Wedgeleaf Thistle Need?
Wedgeleaf Thistle thrives in full sun.
Light Requirement
Full sun
What Temperature and Humidity Does the Wedgeleaf Thistle Prefer?
Cirsium crassicaule grows best at temperatures of 60–80°F. Wedgeleaf Thistle prefers humidity levels of 40–70%.
Temperature
60–80°F
Humidity
40–70%
What Soil Mix Works Best for a Wedgeleaf Thistle?
Well-draining sandy loam with added organic matter. Good drainage is essential for Wedgeleaf Thistle to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Wedgeleaf Thistle?
Feed Wedgeleaf Thistle 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 Wedgeleaf Thistle?
Divide and replant 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 Wedgeleaf Thistle?
Wedgeleaf Thistle can be propagated through seeds. Similar propagation techniques also apply to creeping thistle plant care, which shares the same genus.
Is the Wedgeleaf Thistle Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Wedgeleaf Thistle, 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 Wedgeleaf Thistle?
Wedgeleaf Thistle is susceptible to aphids, thrips, 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 Wedgeleaf Thistle Need?
Wedgeleaf Thistle grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. Wedgeleaf Thistle is native to only a few locations in Kern, Kings, and San Joaquin Counties. In cooler regions, grow Wedgeleaf Thistle as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 13a
Keep exploring plants
Wedgeleaf Thistle 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 Cirsium genus — compare its care with other Cirsium species on PlantoScan.
Cirsium is part of the Asteraceae plant family — browse all Asteraceae genera and species.
Wedgeleaf Thistle thrives in bright light and direct sun — see other bright-light plants.
More Cirsium Species
Other Cirsium species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Cirsium crassicaule Jeps., family Asteraceae (first published in Fl. W. Calif. : 506 (1901)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Wedgeleaf Thistle, 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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