When does Curlycup Gumweed bloom in Utah?

Most often in August. Across 316 dated, research-grade observations of Grindelia squarrosa in Utah, the flowering season runs roughly July to November.

Peak August In flower 316 Examined 404 State Utah

Flowering 316 in flower of 404 examined

25%

70%

63%

95%

100%

92%

97%

86%

67%

Proportion of examined Grindelia squarrosa in Utah in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	2	8	25%	7% to 59%
Feb	0	8	0%	0% to 32%
Mar	0	8	0%	0% to 32%
Apr	2	36	6%	2% to 18%
May	16	23	70%	49% to 84%
Jun	10	16	63%	39% to 82%
Jul	40	42	95%	84% to 99%
Aug	73	73	100%	95% to 100%
Sep	76	83	92%	84% to 96%
Oct	59	61	97%	89% to 99%
Nov	32	37	86%	72% to 94%
Dec	6	9	67%	35% to 88%

Peak flowering in Aug. Each bar is the share of Grindelia squarrosa in Utah 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. 316 of 404 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 Utah found Grindelia squarrosa in flower, not a forecast. It is computed only from observations made in Utah, 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

Grindelia squarrosa

Curlycup Gumweed

Sourcesevery claim on this page

GBIF (iNaturalist Research-grade Observations). Dated flowering annotations in Utah. 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.