When does jimsonweed bloom in New York?

Most often in August. Across 259 dated, research-grade observations of Datura stramonium in New York, the flowering season runs roughly August.

Peak August In flower 259 Examined 623 State New York

Flowering 259 in flower of 623 examined

Proportion of examined Datura stramonium in New York in flower, by month
Month In flower Examined Share 95% interval
Jan 0 18 0% 0% to 18%
Feb 0 5 0% 0% to 43%
Mar 0 5 0% 0% to 43%
Apr 0 8 0% 0% to 32%
May 0 7 0% 0% to 35%
Jun 17 35 49% 33% to 64%
Jul 53 105 50% 41% to 60%
Aug 85 126 67% 59% to 75%
Sep 72 151 48% 40% to 56%
Oct 28 112 25% 18% to 34%
Nov 4 35 11% 5% to 26%
Dec 0 16 0% 0% to 19%

Peak flowering in Aug. Each bar is the share of Datura stramonium in New York 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. 259 of 623 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 New York found Datura stramonium in flower, not a forecast. It is computed only from observations made in New York, 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

Sourcesevery claim on this page

  1. GBIF (iNaturalist Research-grade Observations). Dated flowering annotations in New York. Every record achieved iNaturalist quality grade Research, which is applied upstream at export. 10.15468/dl.wt38fd. Retrieved 2026-07-14.
  2. World Flora Online Plant List. The accepted name. CC0. Retrieved 2026-07-12.