When does yellowdome bloom in California?

Most often in November. Across 681 dated, research-grade observations of Trichoptilium incisum in California, the flowering season runs roughly January to December.

Peak November In flower 681 Examined 705 State California

Flowering 681 in flower of 705 examined

89%

97%

98%

99%

96%

100%

95%

Proportion of examined Trichoptilium incisum in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	62	70	89%	79% to 94%
Feb	163	168	97%	93% to 99%
Mar	235	239	98%	96% to 99%
Apr	94	95	99%	94% to 100%
May	22	23	96%	79% to 99%
Jun	1	1	too few examined
Jul	0	0	too few examined
Aug	0	0	too few examined
Sep	0	0	too few examined
Oct	2	3	too few examined
Nov	31	31	100%	89% to 100%
Dec	71	75	95%	87% to 98%

Peak flowering in Nov. Each bar is the share of Trichoptilium incisum 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. 681 of 705 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 5 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 Trichoptilium incisum 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

Trichoptilium incisum

yellowdome

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.