When does fennel bloom in California?

Most often in July. Across 457 dated, research-grade observations of Foeniculum vulgare in California, the flowering season runs roughly July to September.

Peak July In flower 457 Examined 827 State California

Flowering 457 in flower of 827 examined

26%

27%

10%

52%

97%

94%

83%

76%

64%

54%

Proportion of examined Foeniculum vulgare in California in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	11	43	26%	15% to 40%
Feb	7	26	27%	14% to 46%
Mar	2	51	4%	1% to 13%
Apr	4	103	4%	2% to 10%
May	6	58	10%	5% to 21%
Jun	53	101	52%	43% to 62%
Jul	123	127	97%	92% to 99%
Aug	92	98	94%	87% to 97%
Sep	75	90	83%	74% to 90%
Oct	31	41	76%	61% to 86%
Nov	32	50	64%	50% to 76%
Dec	21	39	54%	39% to 68%

Peak flowering in Jul. Each bar is the share of Foeniculum vulgare 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. 457 of 827 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 Foeniculum vulgare 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

Foeniculum vulgare

fennel

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.