When does Engelmann's Hedgehog Cactus bloom in Arizona?

Most often in April. Across 215 dated, research-grade observations of Echinocereus engelmannii in Arizona, the flowering season runs roughly March to April.

Peak April In flower 215 Examined 420 State Arizona

Flowering 215 in flower of 420 examined

64%

79%

52%

27%

Proportion of examined Echinocereus engelmannii in Arizona in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	14	0%	0% to 22%
Feb	0	18	0%	0% to 18%
Mar	88	137	64%	56% to 72%
Apr	107	135	79%	72% to 85%
May	16	31	52%	35% to 68%
Jun	4	15	27%	11% to 52%
Jul	0	7	0%	0% to 35%
Aug	0	1	too few examined
Sep	0	8	0%	0% to 32%
Oct	0	17	0%	0% to 18%
Nov	0	10	0%	0% to 28%
Dec	0	27	0%	0% to 12%

Peak flowering in Apr. Each bar is the share of Echinocereus engelmannii 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. 215 of 420 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. One month has fewer than 5 examined observations, so no proportion is drawn for it. 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 Echinocereus engelmannii 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

Echinocereus engelmannii

Engelmann's Hedgehog 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.