Milk Thistle (Silybum marianum) is in the Sunflowers, Daisies, Asters, and Allies family (Asteraceae). Across the U.S., iNaturalist users have logged 4,326 research-grade flowering observations of it in our sample, peaking in May.
Nationally it blooms mainly from April to June, but timing varies a lot by state and elevation — see the table below.
When to photograph Milk Thistle: observations by month (U.S.)
About Milk Thistle
Silybum marianum has other common names include cardus marianus, milk thistle, blessed milkthistle, Marian thistle, Mary thistle, Saint Mary's thistle, Mediterranean milk thistle, variegated thistle and Scotch thistle. This species is an annual or biennial plant of the Asteraceae family. This fairly typical thistle has red to purple flowers and shiny pale green leaves with white veins. Originally a native of Southern Europe through to Asia, it is now found throughout the world.From Wikipedia via iNaturalist — article, CC BY-SA.
Milk Thistle by state
| State | Observations | Peak month | Main season |
|---|---|---|---|
| California | 4,097 | May | Apr–Jun |
| Texas | 122 | April | Apr–Apr |
| Oregon | 95 | June | May–Jun |
| Arizona | 6 | June | Jun–Jun |
Main season = months with at least 30% of the state's peak-month count.
Related wildflowers (Sunflowers, Daisies, Asters, and Allies)
black-eyed Susan
Common Yarrow
White Snakeroot
Chicory
Lawn daisy
Philadelphia fleabane
Pearly Everlasting
Blue Mistflower
Photography tips
- Photograph flowers on calm, overcast mornings to avoid wind blur and harsh shadows.
- Get low: a shallow depth of field (f/2.8–f/5.6) isolates a bloom against soft color.
- Stay on trails — trampling meadows kills plants and ruins next year's display.
- Try a kaleidoscope abstract of a single bloom with our online kaleidoscope tool.
FAQ
When is the best time to photograph Milk Thistle?
Nationally, May has the most observations, with the main season from April to June.
Where is Milk Thistle most often seen?
The most observations come from California, Texas, Oregon.