When does creeping mahonia bloom in Colorado?

Most often in April. Across 331 dated, research-grade observations of Berberis repens in Colorado, the flowering season runs roughly March to June.

Peak April In flower 331 Examined 828 State Colorado

Flowering 331 in flower of 828 examined

10%

21%

68%

78%

77%

66%

Proportion of examined Berberis repens in Colorado in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	4	39	10%	4% to 24%
Feb	3	14	21%	8% to 48%
Mar	43	63	68%	56% to 78%
Apr	73	93	78%	69% to 86%
May	107	139	77%	69% to 83%
Jun	93	140	66%	58% to 74%
Jul	5	87	6%	2% to 13%
Aug	0	83	0%	0% to 4%
Sep	1	45	2%	0% to 12%
Oct	0	62	0%	0% to 6%
Nov	1	30	3%	1% to 17%
Dec	1	33	3%	1% to 15%

Peak flowering in Apr. Each bar is the share of Berberis repens in Colorado 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. 331 of 828 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 Colorado found Berberis repens in flower, not a forecast. It is computed only from observations made in Colorado, 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

Berberis repens

creeping mahonia

Sourcesevery claim on this page

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