When does white ratany bloom in California?

Most often in May. Across 580 dated, research-grade observations of Krameria bicolor in California, the flowering season runs roughly April to August.

Peak May In flower 580 Examined 989 State California

Flowering 580 in flower of 989 examined

22%

46%

56%

87%

92%

73%

50%

88%

56%

64%

58%

41%

Proportion of examined Krameria bicolor in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	26	116	22%	16% to 31%
Feb	51	112	46%	37% to 55%
Mar	85	151	56%	48% to 64%
Apr	115	132	87%	80% to 92%
May	106	115	92%	86% to 96%
Jun	11	15	73%	48% to 89%
Jul	4	8	50%	22% to 78%
Aug	7	8	88%	53% to 98%
Sep	15	27	56%	37% to 72%
Oct	47	74	64%	52% to 74%
Nov	64	110	58%	49% to 67%
Dec	49	121	41%	32% to 49%

Peak flowering in May. Each bar is the share of Krameria bicolor 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. 580 of 989 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 Krameria bicolor 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

Krameria bicolor

white ratany

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.