When does Common Cat's-ear bloom in California?

Most often in August. Across 192 dated, research-grade observations of Hypochaeris radicata in California, the flowering season runs roughly February to December.

Peak August In flower 192 Examined 228 State California

Flowering 192 in flower of 228 examined

73%

80%

79%

65%

93%

91%

100%

91%

92%

89%

Proportion of examined Hypochaeris radicata in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	11	15	73%	48% to 89%
Feb	8	10	80%	49% to 94%
Mar	11	14	79%	52% to 92%
Apr	33	51	65%	51% to 76%
May	26	28	93%	77% to 98%
Jun	25	27	93%	77% to 98%
Jul	21	23	91%	73% to 98%
Aug	10	10	100%	72% to 100%
Sep	17	17	100%	82% to 100%
Oct	10	11	91%	62% to 98%
Nov	12	13	92%	67% to 99%
Dec	8	9	89%	56% to 98%

Peak flowering in Aug. Each bar is the share of Hypochaeris radicata in California observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 192 of 228 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.wt38fd.

What this is, and what it is not

This is a record of when people in California found Hypochaeris radicata in flower, not a forecast. It is computed only from observations made in California, so it is not the species’ global average dragged onto a map: the same plant flowers on different dates in different places, and that is the entire point of the page.

It will not tell you what your particular plant will do this year. Bloom time moves with the season, with altitude, and with the weather, and a warm February pulls everything forward. We publish the distribution and the sample size, and we refuse to draw a month that too few people examined.

The plant

Hypochaeris radicata

Common Cat's-ear

Sourcesevery claim on this page

GBIF (iNaturalist Research-grade Observations). Dated flowering annotations in California. Every record achieved iNaturalist quality grade Research, which is applied upstream at export. 10.15468/dl.wt38fd. Retrieved 2026-07-14.
World Flora Online Plant List. The accepted name. CC0. Retrieved 2026-07-12.