Native·Monarch value ·Garden ·Nectar

Hall’s Milkweed

Asclepias hallii A. Gray

A handsome southern Rocky Mountain endemic with soft pink-mauve flower clusters and grayish lance-shaped leaves, growing on dry mesas, sandy foothills and piñon-juniper edges from Colorado to Nevada.

Also called Purple Silkweed.

Hall’s Milkweed (Asclepias hallii). Fort Bayard - Flickr - aspidoscelis (20) — Patrick Alexander from Las Cruces, NM · CC0 · Wikimedia Commons

Height: 1.5 ft–3 ft
Spread: 1.5 ft–3 ft
Flowers: pink, mauve
Bloom: June to August
Light: Full sun
Soil moisture: Dry
USDA zones: 4–8
Leaves: Opposite, lanceolate
Sap: Milky latex
Roots: Rhizomatous, spreads by root
Stratification: 30 days cold-moist
Range: 6 states

When it flowers

Hall’s Milkweed blooms June to August, peaking in July.

JFMAMJJASOND

How to identify it

Resembles a slimmer, drier-country showy milkweed with narrower leaves and smaller flowers.
Flower clusters are terminal and upright, pale pink to dull rose.
Stems often several from a spreading rootstock, sometimes forming loose colonies.

Diagram of Hall’s Milkweed showing opposite lanceolate leaves and pink flower clusters — **Diagnostic plate** Drawn from this species' own characters: **opposite** leaves, **lanceolate** in shape, a single upright stem, with pink to mauve umbels. Sap is milky.

Hall’s Milkweed (Asclepias hallii). Near Border Hill - Flickr - aspidoscelis — Patrick Alexander from Las Cruces, NM · CC0 · Wikimedia Commons

Hall’s Milkweed (Asclepias hallii). Fort Stanton Mesa - Flickr - aspidoscelis — Patrick Alexander from Las Cruces, NM · CC0 · Wikimedia Commons

Hall’s Milkweed (Asclepias hallii). Near Ft. Stanton - Flickr - aspidoscelis (4) — Patrick Alexander from Las Cruces, NM · CC0 · Wikimedia Commons

Hall’s Milkweed (Asclepias hallii). Hall’s Milkweed photographed in Colorado, US — Ryan Sorrells · CC BY 4.0 · iNaturalist

Hall’s Milkweed (Asclepias hallii). Hall’s Milkweed photographed in Chaffee County, US-CO, US — Public domain (CC0) · CC0 · iNaturalist

Hall’s Milkweed (Asclepias hallii). Hall’s Milkweed photographed in Fremont County, CO, USA — Anders Hastings · CC BY 4.0 · iNaturalist

Hall’s Milkweed (Asclepias hallii). Hall’s Milkweed photographed in Arkansas River Trail, Buena Vista, CO, US — Brad Grimm · CC BY 4.0 · iNaturalist

Ecology and wildlife value

A significant monarch host on Colorado’s Western Slope and across the Colorado Plateau, where large-leaved milkweeds are scarce.

Growing hall’s milkweed

Excellent for xeric gardens in the Interior West, though seed is hard to source. Needs sharp drainage and full sun.

Seed needs about 30 days of cold-moist stratification. Rhizomatous, spreads by root. See how to plant milkweed seed for the full method.

Cautions

Standard milkweed cautions. More on milkweed toxicity.

Where hall’s milkweed grows

Recorded in 6 states: Arizona, Colorado, New Mexico, Nevada, Utah, Wyoming.

AK ME VT NH WA ID MT ND MN IL WI MI NY MA RI OR NV WY SD IA IN OH PA NJ CT CA UT CO NE MO KY WV VA MD DE AZ NM KS AR TN NC SC DC TX OK LA MS AL GA HI FL

Distribution is generalized to state level. For county-level maps see USDA PLANTS and BONAP.

References and further reading

Names, ranges and conservation status here are drawn from the databases below. Where those disagree with a regional flora, trust the flora.

Plants of the World Online 94337-1. Royal Botanic Gardens, Kew. Accepted name, authorship and global distribution.
GBIF 3170237. Global Biodiversity Information Facility. Aggregated occurrence records.
iNaturalist 158741. Community observations, photographs and phenology.
BONAP county distribution map. Biota of North America Program. County-level range map.
NatureServe Explorer. Conservation status ranks at global and state level.
World Flora Online. Nomenclature and synonymy.
Woodson, R. E. (1954). The North American species of Asclepias L.. Annals of the Missouri Botanical Garden 41(1): 1–211. The monograph the modern taxonomy of the genus still rests on. View
Flora of North America Editorial Committee (eds.) (2026). Flora of North America North of Mexico. Oxford University Press, New York and Oxford. Accepted names, keys and descriptions for the North American flora. View
Royal Botanic Gardens, Kew (2026). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Nomenclature and global distribution, keyed to IPNI name identifiers. View
Kartesz, J. T. (Biota of North America Program) (2026). North American Plant Atlas. BONAP, Chapel Hill, North Carolina. County-level distribution maps, the basis for the ranges generalized here. View
USDA, NRCS (2026). The PLANTS Database. National Plant Data Team, Greensboro, North Carolina. State-level distribution, wetland status and nomenclature. View
Agrawal, A. A. (2017). Monarchs and Milkweed: A Migrating Butterfly, a Poisonous Plant, and Their Remarkable Story of Coevolution. Princeton University Press. The standard general account of the milkweed and monarch relationship. View

Cite this page

This page is licensed CC BY 4.0. Quote it, adapt it and reuse it, including commercially, as long as you credit Milkweed USA and link back.

APA

Milkweed USA. (2026). Hall’s Milkweed (Asclepias hallii). Retrieved DATE, from https://milkweedusa.com/species/halls-milkweed/

MLA

"Hall’s Milkweed (Asclepias hallii)." Milkweed USA, 2026, https://milkweedusa.com/species/halls-milkweed/. Accessed DATE.

Chicago

Milkweed USA. "Hall’s Milkweed (Asclepias hallii)." Last modified 2026-08-01. Accessed DATE. https://milkweedusa.com/species/halls-milkweed/.

BibTeX

@misc{milkweedusa_specieshallsmilkweed,
  title  = {Hall’s Milkweed (Asclepias hallii)},
  author = {{Milkweed USA}},
  year   = {2026},
  url    = {https://milkweedusa.com/species/halls-milkweed/},
  note   = {Accessed DATE}
}