When does Cliff Aster bloom in California?

Most often in October. Across 309 dated, research-grade observations of Malacothrix saxatilis in California, the flowering season runs roughly January to December.

Peak October In flower 309 Examined 351 State California

Flowering 309 in flower of 351 examined

90%

50%

59%

70%

88%

94%

96%

97%

90%

100%

94%

98%

Proportion of examined Malacothrix saxatilis in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	26	29	90%	74% to 96%
Feb	7	14	50%	27% to 73%
Mar	13	22	59%	39% to 77%
Apr	19	27	70%	52% to 84%
May	46	52	88%	77% to 95%
Jun	29	31	94%	79% to 98%
Jul	24	25	96%	80% to 99%
Aug	34	35	97%	85% to 99%
Sep	19	21	90%	71% to 97%
Oct	21	21	100%	85% to 100%
Nov	29	31	94%	79% to 98%
Dec	42	43	98%	88% to 100%

Peak flowering in Oct. Each bar is the share of Malacothrix saxatilis 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. 309 of 351 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 Malacothrix saxatilis 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

Malacothrix saxatilis

Cliff Aster

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.