When does Felt Paintbrush bloom in California?

Most often in May. Across 1,045 dated, research-grade observations of Castilleja foliolosa in California, the flowering season runs roughly January to December.

Peak May In flower 1,045 Examined 1,094 State California

Flowering 1,045 in flower of 1,094 examined

96%

93%

96%

98%

99%

94%

96%

86%

36%

81%

Proportion of examined Castilleja foliolosa in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	45	47	96%	86% to 99%
Feb	145	156	93%	88% to 96%
Mar	242	253	96%	92% to 98%
Apr	298	303	98%	96% to 99%
May	180	181	99%	97% to 100%
Jun	79	84	94%	87% to 97%
Jul	24	25	96%	80% to 99%
Aug	2	3	too few examined
Sep	3	3	too few examined
Oct	6	7	86%	49% to 97%
Nov	4	11	36%	15% to 65%
Dec	17	21	81%	60% to 92%

Peak flowering in May. Each bar is the share of Castilleja foliolosa 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. 1,045 of 1,094 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 2 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 Castilleja foliolosa 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

Castilleja foliolosa

Felt Paintbrush

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.