When does Spanish clover bloom in California?

Most often in July. Across 777 dated, research-grade observations of Acmispon americanus in California, the flowering season runs roughly June to November.

Peak July In flower 777 Examined 932 State California

Flowering 777 in flower of 932 examined

26%

70%

92%

99%

95%

93%

89%

Proportion of examined Acmispon americanus in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	1	too few examined
Feb	0	1	too few examined
Mar	1	16	6%	1% to 28%
Apr	20	77	26%	17% to 37%
May	116	166	70%	63% to 76%
Jun	197	214	92%	88% to 95%
Jul	250	252	99%	97% to 100%
Aug	104	110	95%	89% to 97%
Sep	55	58	95%	86% to 98%
Oct	25	27	93%	77% to 98%
Nov	8	9	89%	56% to 98%
Dec	1	1	too few examined

Peak flowering in Jul. Each bar is the share of Acmispon americanus 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. 777 of 932 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 3 months have fewer than 5 examined observations, so no proportion is drawn for them. 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 Acmispon americanus 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

Acmispon americanus

Spanish clover

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.