When does bluewitch nightshade bloom in California?

Most often in March. Across 1,882 dated, research-grade observations of Solanum umbelliferum in California, the flowering season runs roughly January to December.

Peak March In flower 1,882 Examined 1,994 State California

Flowering 1,882 in flower of 1,994 examined

93%

98%

99%

97%

93%

83%

54%

64%

78%

93%

69%

89%

Proportion of examined Solanum umbelliferum in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	130	140	93%	87% to 96%
Feb	283	289	98%	96% to 99%
Mar	517	524	99%	97% to 99%
Apr	484	498	97%	95% to 98%
May	258	277	93%	90% to 96%
Jun	89	107	83%	75% to 89%
Jul	21	39	54%	39% to 68%
Aug	9	14	64%	39% to 84%
Sep	14	18	78%	55% to 91%
Oct	28	30	93%	79% to 98%
Nov	9	13	69%	42% to 87%
Dec	40	45	89%	77% to 95%

Peak flowering in Mar. Each bar is the share of Solanum umbelliferum in California 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. 1,882 of 1,994 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 California found Solanum umbelliferum in flower, not a forecast. It is computed only from observations made in California, 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

Solanum umbelliferum

bluewitch nightshade

Sourcesevery claim on this page

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