How much sun does Cobweb thistle need?

Cobweb thistle grows best in full sun conditions.

When does Cobweb thistle bloom?

Cobweb thistle blooms in April, May, June, and July.

Where is Cobweb thistle native?

Cobweb thistle (Cirsium occidentale) is native to CA, NV, OR, per vouchered herbarium specimen records and regional native plant society lists.

What butterflies or moths does Cobweb thistle host?

Cobweb thistle is a larval host plant for painted lady.

Cobweb thistle

Name: Pollinator Patch
Author: Pollinator Patch

Cirsium occidentale

Last reviewed: September 2026

Cobweb thistle (Cirsium occidentale) is a biennial forb native to CA, NV, OR. It blooms in April, May, June, and July. The flowers draw hummingbirds, bees, and butterflies.

Toxicity unknown

Cobweb thistle (Cirsium occidentale) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.

Light

full sun

Water

low

Size

12"–48" H × 12"–24" W

Bloom

Apr, May, Jun, Jul

Native to

CA, NV, OR

Pollinators

hummingbirds, bees, butterflies

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Browse plants for this ecoregion

Coast Range Northwestern Forested Mountains Sierra Nevada Central California Foothills and Coastal Mountains Central California Valley Southern California Mountains Central Basin and Range Mojave Basin and Range North American Deserts Sonoran Basin and Range Southern California/Northern Baja Coast

A spiny biennial thistle with deeply lobed, woolly gray-green leaves and large cobwebby flower heads in shades of red to cream. Forms a basal rosette the first year and sends up a tall flowering stalk the second, growing on dry slopes and coastal bluffs.

Growing Cobweb thistle

Grow Cobweb thistle in full sun and low water. Mature plants reach 12 to 48 inches tall and spread 12 to 24 inches wide.

Wildlife value

Host plant for painted lady.

Nectar-rich blooms draw hummingbirds and a wide range of native bees and butterflies, and the foliage serves as a larval host for painted lady caterpillars.

Common questions

How much sun does Cobweb thistle need?: Cobweb thistle grows best in full sun conditions.
When does Cobweb thistle bloom?: Cobweb thistle blooms in April, May, June, and July.
Where is Cobweb thistle native?: Cobweb thistle (Cirsium occidentale) is native to CA, NV, OR, per vouchered herbarium specimen records and regional native plant society lists.
What butterflies or moths does Cobweb thistle host?: Cobweb thistle is a larval host plant for painted lady.

Native range data from vouchered herbarium specimen records and regional native plant society lists. Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

If something looks wrong

Common plant problems, and what to check first

These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.

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