When does Day Flower bloom in California?

Most often in August. Across 300 dated, research-grade observations of Commelina benghalensis in California, the flowering season runs roughly January to December.

Peak August In flower 300 Examined 326 State California

Flowering 300 in flower of 326 examined

82%

93%

91%

96%

89%

94%

89%

100%

93%

95%

71%

100%

Proportion of examined Commelina benghalensis in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	9	11	82%	52% to 95%
Feb	14	15	93%	70% to 99%
Mar	39	43	91%	78% to 96%
Apr	50	52	96%	87% to 99%
May	62	70	89%	79% to 94%
Jun	32	34	94%	81% to 98%
Jul	16	18	89%	67% to 97%
Aug	19	19	100%	83% to 100%
Sep	25	27	93%	77% to 98%
Oct	20	21	95%	77% to 99%
Nov	5	7	71%	36% to 92%
Dec	9	9	100%	70% to 100%

Peak flowering in Aug. Each bar is the share of Commelina benghalensis 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. 300 of 326 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 Commelina benghalensis 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

Commelina benghalensis

Day Flower

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.