When does butterfly milkweed bloom in Florida?

Most often in May. Across 378 dated, research-grade observations of Asclepias tuberosa in Florida, the flowering season runs roughly March to October.

Peak May In flower 378 Examined 417 State Florida

Flowering 378 in flower of 417 examined

88%

94%

96%

88%

87%

90%

86%

Proportion of examined Asclepias tuberosa in Florida in flower, by month
Month	In flower	Examined	Share	95% interval
Jan	4	4	too few examined
Feb	2	2	too few examined
Mar	15	17	88%	66% to 97%
Apr	44	47	94%	83% to 98%
May	121	126	96%	91% to 98%
Jun	64	73	88%	78% to 93%
Jul	33	38	87%	73% to 94%
Aug	36	40	90%	77% to 96%
Sep	37	43	86%	73% to 93%
Oct	19	22	86%	67% to 95%
Nov	1	2	too few examined
Dec	2	3	too few examined

Peak flowering in May. Each bar is the share of Asclepias tuberosa in Florida 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. 378 of 417 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 4 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 Florida found Asclepias tuberosa in flower, not a forecast. It is computed only from observations made in Florida, 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

Asclepias tuberosa

butterfly milkweed

Sourcesevery claim on this page

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