When does Douglas's milkvetch bloom in California?

Most often in March. Across 231 dated, research-grade observations of Astragalus douglasii in California, the flowering season runs roughly February to May.

Peak March In flower 231 Examined 344 State California

Flowering 231 in flower of 344 examined

50%

88%

92%

77%

83%

51%

52%

50%

63%

50%

Proportion of examined Astragalus douglasii in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	3	6	50%	19% to 81%
Feb	7	8	88%	53% to 98%
Mar	34	37	92%	79% to 97%
Apr	37	48	77%	63% to 87%
May	57	69	83%	72% to 90%
Jun	38	75	51%	40% to 62%
Jul	26	50	52%	39% to 65%
Aug	5	10	50%	24% to 76%
Sep	8	16	50%	28% to 72%
Oct	10	16	63%	39% to 82%
Nov	3	6	50%	19% to 81%
Dec	3	3	too few examined

Peak flowering in Mar. Each bar is the share of Astragalus douglasii 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. 231 of 344 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. One month has fewer than 5 examined observations, so no proportion is drawn for it. 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 Astragalus douglasii 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

Astragalus douglasii

Douglas's milkvetch

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.