When does Sea Bindweed bloom in California?

Most often in June. Across 337 dated, research-grade observations of Calystegia soldanella in California, the flowering season runs roughly April to June.

Peak June In flower 337 Examined 491 State California

Flowering 337 in flower of 491 examined

27%

53%

52%

84%

89%

90%

65%

29%

18%

38%

Proportion of examined Calystegia soldanella in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	3	11	27%	10% to 57%
Feb	8	15	53%	30% to 75%
Mar	13	25	52%	34% to 70%
Apr	58	69	84%	74% to 91%
May	106	119	89%	82% to 94%
Jun	104	116	90%	83% to 94%
Jul	28	43	65%	50% to 78%
Aug	9	31	29%	16% to 47%
Sep	5	28	18%	8% to 36%
Oct	0	16	0%	0% to 19%
Nov	0	10	0%	0% to 28%
Dec	3	8	38%	14% to 69%

Peak flowering in Jun. Each bar is the share of Calystegia soldanella 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. 337 of 491 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 Calystegia soldanella 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

Calystegia soldanella

Sea Bindweed

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.