When does California Barrel Cactus bloom in Arizona?

Most often in June. Across 111 dated, research-grade observations of Ferocactus acanthodes in Arizona, the flowering season runs roughly May to September.

Peak June In flower 111 Examined 321 State Arizona

Flowering 111 in flower of 321 examined

21%

41%

70%

81%

61%

77%

67%

15%

13%

Proportion of examined Ferocactus acanthodes in Arizona in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	19	0%	0% to 17%
Feb	0	16	0%	0% to 19%
Mar	12	58	21%	12% to 33%
Apr	18	44	41%	28% to 56%
May	26	37	70%	54% to 83%
Jun	17	21	81%	60% to 92%
Jul	14	23	61%	41% to 78%
Aug	10	13	77%	50% to 92%
Sep	6	9	67%	35% to 88%
Oct	4	27	15%	6% to 32%
Nov	3	23	13%	5% to 32%
Dec	1	31	3%	1% to 16%

Peak flowering in Jun. Each bar is the share of Ferocactus acanthodes in Arizona 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. 111 of 321 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 Arizona found Ferocactus acanthodes in flower, not a forecast. It is computed only from observations made in Arizona, 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

Ferocactus acanthodes

California Barrel Cactus

Sourcesevery claim on this page

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