When does Palmer penstemon bloom in Utah?

Most often in April. Across 179 dated, research-grade observations of Penstemon palmeri in Utah, the flowering season runs roughly April to June.

Peak April In flower 179 Examined 225 State Utah

Flowering 179 in flower of 225 examined

20%

100%

89%

93%

68%

29%

Proportion of examined Penstemon palmeri in Utah in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	0	1	too few examined
Feb	0	2	too few examined
Mar	2	10	20%	6% to 51%
Apr	15	15	100%	80% to 100%
May	62	70	89%	79% to 94%
Jun	83	89	93%	86% to 97%
Jul	13	19	68%	46% to 85%
Aug	1	4	too few examined
Sep	0	3	too few examined
Oct	2	7	29%	8% to 64%
Nov	1	2	too few examined
Dec	0	3	too few examined

Peak flowering in Apr. Each bar is the share of Penstemon palmeri in Utah 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. 179 of 225 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 6 months have fewer than 5 examined observations, so no proportion is drawn for them. 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 Utah found Penstemon palmeri in flower, not a forecast. It is computed only from observations made in Utah, 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

Penstemon palmeri

Palmer penstemon

Sourcesevery claim on this page

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