When does Thick-leaved Yerba Santa bloom in California?

Most often in April. Across 439 dated, research-grade observations of Eriodictyon crassifolium in California, the flowering season runs roughly April to June.

Peak April In flower 439 Examined 820 State California

Flowering 439 in flower of 820 examined

30%

62%

83%

82%

79%

27%

Proportion of examined Eriodictyon crassifolium in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	4	55	7%	3% to 17%
Feb	18	61	30%	20% to 42%
Mar	87	140	62%	54% to 70%
Apr	157	190	83%	77% to 87%
May	112	137	82%	74% to 87%
Jun	56	71	79%	68% to 87%
Jul	4	15	27%	11% to 52%
Aug	1	26	4%	1% to 19%
Sep	0	29	0%	0% to 12%
Oct	0	38	0%	0% to 9%
Nov	0	20	0%	0% to 16%
Dec	0	38	0%	0% to 9%

Peak flowering in Apr. Each bar is the share of Eriodictyon crassifolium 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. 439 of 820 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 Eriodictyon crassifolium 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

Eriodictyon crassifolium

Thick-leaved Yerba Santa

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.