When does starry rosinweed bloom in North Carolina?

Most often in August. Across 139 dated, research-grade observations of Silphium asteriscus in North Carolina, the flowering season runs roughly June to September.

Peak August In flower 139 Examined 152 State North Carolina

Flowering 139 in flower of 152 examined

92%

97%

100%

83%

Proportion of examined Silphium asteriscus in North Carolina in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	0	too few examined
Feb	0	0	too few examined
Mar	0	0	too few examined
Apr	0	2	too few examined
May	1	1	too few examined
Jun	34	37	92%	79% to 97%
Jul	61	63	97%	89% to 99%
Aug	32	32	100%	89% to 100%
Sep	10	12	83%	55% to 95%
Oct	1	3	too few examined
Nov	0	2	too few examined
Dec	0	0	too few examined

Peak flowering in Aug. Each bar is the share of Silphium asteriscus in North Carolina 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. 139 of 152 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 8 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 North Carolina found Silphium asteriscus in flower, not a forecast. It is computed only from observations made in North Carolina, 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

Silphium asteriscus

starry rosinweed

Sourcesevery claim on this page

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