When does Drummond's wild petunia bloom in Texas?

Most often in August. Across 175 dated, research-grade observations of Ruellia drummondiana in Texas, the flowering season runs roughly June to October.

Peak August In flower 175 Examined 184 State Texas

Flowering 175 in flower of 184 examined

83%

85%

100%

98%

97%

Proportion of examined Ruellia drummondiana in Texas 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	0	too few examined
May	4	4	too few examined
Jun	10	12	83%	55% to 95%
Jul	22	26	85%	66% to 94%
Aug	52	52	100%	93% to 100%
Sep	54	55	98%	90% to 100%
Oct	33	34	97%	85% to 99%
Nov	0	1	too few examined
Dec	0	0	too few examined

Peak flowering in Aug. Each bar is the share of Ruellia drummondiana in Texas 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. 175 of 184 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 7 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 Texas found Ruellia drummondiana in flower, not a forecast. It is computed only from observations made in Texas, 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

Ruellia drummondiana

Drummond's wild petunia

Sourcesevery claim on this page

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