North America Native Plant

Cobwebby Thistle

Botanical name: Cirsium occidentale var. occidentale

USDA symbol: CIOCO

Life cycle: biennial

Habit: forb

Native status: Native to the lower 48 states  

Synonyms: Cirsium coulteri Harv. & A. Gray (CICO6)   

Cobwebby Thistle: A Striking California Native for Wildlife Gardens Meet the cobwebby thistle (Cirsium occidentale var. occidentale), a fascinating California native that’s sure to turn heads in your garden – and not just because it’s a thistle! This biennial wildflower brings unique beauty and important ecological value to native plant ...

Rare plant alert!

Region: Conservation status by state

Status: S3S4T3T4: Status is uncertain but is somewhere between the following rankings: Vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals ⚘ Subspecies or variety is vulnerable: Either very rare and local throughout its range, found only in a restricted range (even if abundant at some locations), or factors are making it vulnerable to extinction. Typically 21 to 100 occurrences or between 3,000 and 10,000 individuals. ⚘ Apparently Secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the state or more than 10,000 individuals ⚘ Subspecies or varieties is apparently secure: Uncommon but not rare, and usually widespread. Possibly cause for longterm concern. Typically more than 100 occurrences in the region or more than 10,000 individuals ⚘

Cobwebby Thistle: A Striking California Native for Wildlife Gardens

Meet the cobwebby thistle (Cirsium occidentale var. occidentale), a fascinating California native that’s sure to turn heads in your garden – and not just because it’s a thistle! This biennial wildflower brings unique beauty and important ecological value to native plant landscapes, though it comes with a few considerations worth knowing about.

What Makes Cobwebby Thistle Special

Don’t let the word thistle scare you away from this remarkable native plant. The cobwebby thistle gets its charming common name from the distinctive white, web-like hairs that cover its stems and leaves, creating an almost ethereal appearance. These silvery-white fibers give the entire plant a soft, fuzzy texture that’s quite different from the harsh, spiny reputation most thistles have.

As a biennial forb, cobwebby thistle follows a two-year life cycle. In its first year, it forms a low rosette of leaves, then sends up flowering stems in its second year before setting seed and completing its cycle. The purple-pink flower heads bloom atop sturdy stems, creating a lovely contrast against the silvery foliage.

Where Cobwebby Thistle Calls Home

This thistle is a true California native, found naturally throughout the Golden State’s diverse landscapes. From coastal areas to inland foothills, cobwebby thistle has adapted to California’s Mediterranean climate and varied terrain.

Why Consider Cobwebby Thistle for Your Garden

If you’re creating a native California garden or wildlife habitat, cobwebby thistle offers several compelling benefits:

  • Pollinator magnet: The nectar-rich flowers attract butterflies, native bees, and other beneficial insects
  • Low maintenance: Once established, it’s quite drought-tolerant and needs minimal care
  • Unique appearance: The cobwebby texture adds interesting visual and tactile elements to plantings
  • Native authenticity: Supports local ecosystems and wildlife that co-evolved with this species

Important Conservation Considerations

Here’s something crucial to know: cobwebby thistle has a conservation status that suggests some populations may be at risk. This means it’s more important than ever to source this plant responsibly. If you’re interested in growing cobwebby thistle, make sure to:

  • Purchase from reputable native plant nurseries
  • Never collect seeds or plants from wild populations
  • Choose nursery-propagated specimens with known provenance
  • Consider it a special addition that supports conservation efforts

Growing Cobwebby Thistle Successfully

Cobwebby thistle thrives in USDA zones 8-10, making it perfect for most California gardens. Here’s how to give it the best growing conditions:

Sun and Soil: Plant in full sun to partial shade with well-draining soil. Like many California natives, it prefers not to have wet feet, especially during summer dormancy periods.

Water Needs: While young plants need regular water to get established, mature cobwebby thistle is quite drought-tolerant. Follow typical California native watering practices – more water in winter and spring, less in summer.

Planting Tips: The easiest way to grow cobwebby thistle is from seed sown in fall, mimicking natural germination patterns. The seeds need the cool, moist conditions of winter to break dormancy and sprout in spring.

Garden Design Ideas

Cobwebby thistle works beautifully in:

  • Native wildflower meadows
  • Pollinator gardens paired with other California natives
  • Naturalized areas where it can self-seed
  • Wildlife habitat gardens
  • Drought-tolerant landscape designs

Is Cobwebby Thistle Right for Your Garden?

This native thistle is ideal for gardeners who want to support California’s native ecosystems while adding unique texture and pollinator value to their landscapes. Its relatively rare status makes it a special choice for conservation-minded gardeners willing to source it responsibly.

Just remember that as a biennial, individual plants won’t be permanent fixtures – but if conditions are right, cobwebby thistle may self-seed and create a sustainable population in your garden. For gardeners seeking low-maintenance natives with ecological value and distinctive beauty, cobwebby thistle is definitely worth considering.

Cobwebby Thistle

Classification

Group

Dicot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Magnoliopsida - Dicotyledons

Subclass

Asteridae

Order

Asterales

Family

Asteraceae Bercht. & J. Presl - Aster family

Genus

Cirsium Mill. - thistle

Species

Cirsium occidentale (Nutt.) Jeps. - cobwebby thistle

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA