When does grey-headed coneflower bloom in Illinois?

Most often in July. Across 160 dated, research-grade observations of Ratibida pinnata in Illinois, the flowering season runs roughly July to October.

Peak July In flower 160 Examined 231 State Illinois

Flowering 160 in flower of 231 examined

67%

96%

88%

40%

89%

Proportion of examined Ratibida pinnata in Illinois in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	10	0%	0% to 28%
Feb	0	1	too few examined
Mar	0	6	0%	0% to 39%
Apr	0	15	0%	0% to 20%
May	0	5	0%	0% to 43%
Jun	16	24	67%	47% to 82%
Jul	92	96	96%	90% to 98%
Aug	38	43	88%	76% to 95%
Sep	6	15	40%	20% to 64%
Oct	8	9	89%	56% to 98%
Nov	0	2	too few examined
Dec	0	5	0%	0% to 43%

Peak flowering in Jul. Each bar is the share of Ratibida pinnata in Illinois 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. 160 of 231 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 Illinois found Ratibida pinnata in flower, not a forecast. It is computed only from observations made in Illinois, 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

Ratibida pinnata

grey-headed coneflower

Sourcesevery claim on this page

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