Based on 4,097 research-grade iNaturalist flowering observations in California, Milk Thistle blooms mainly from April to June, peaking in May. It ranks #34 among wildflowers recorded in the state in our data.
Silybum marianum
Milk Thistle in California by month
Bars show research-grade observations per month. They mix true seasonality with how often people are outdoors, so treat small numbers with caution.
Also in bloom in California in May
Ithuriel's Spear
White Globe Lily
Yellow Mariposa Lily
Butterfly Mariposa Lily
California poppy
Chaparral Yucca
Redstem Stork's-bill
Blue Elder
Places to look in California
Botanical GardenThe Huntington Library, Art Museum, and Botanical Gardens
State ParkHearst Castle
Botanical GardenSan Francisco Botanical Garden
State ParkAnza-Borrego Desert State Park
National ForestAngeles National Forest
National ForestSequoia National Forest
FAQ
When does Milk Thistle bloom in California?
Mainly April–June, with the most records in May.
How common is Milk Thistle in California?
It ranks #34 by number of iNaturalist flowering observations among wildflowers in California (4,097 records in our sample).